The oxidation and reduction behaviors of sintered (Pu{sub 0.3}U{sub 0.7})O{sub 2-x} pellets have been studied at 1873 K under a controlled oxygen partial pressure. From the results of oxygen-to-metal (O/M) ratio changes, dimensional and structural changes, it was concluded that the crack nucleation-propagation and the local density change of pores were caused by the tensile and compressive stresses due to the O/M ratio distribution in the direction of the pellet radius. (authors)

We present elastic properties, theoretical and experimental, of Pu metal and Pu-Ga ({delta}) alloys together with ab initio equilibrium equation-of-state for these systems. For the theoretical treatment we employ density-functional theory in conjunction with spin-orbit coupling and orbital polarization for the metal and coherent-potential approximation for the alloys. Pu and Pu-Ga alloys are also investigated experimentally using resonant ultrasound spectroscopy. We show that orbital correlations become more important proceeding from {alpha} {yields} {beta} {yields} {gamma} plutonium, thus suggesting increasing f-electron correlation (localization). For the {delta}-Pu-Ga alloys we find a softening with larger Ga content, i.e., atomic volume, bulk modulus, and elastic constants, suggest a weakened chemical bonding with addition of Ga. Our measurements confirm qualitatively the theory but uncertainties remain when comparing the model with experiments.

The investigation of physical properties of uranium and plutonium mixed oxide (MOX) fuels is important for the development of fast reactor fuels. It is well known that MOX is a nonstoichiometric oxide, and the physical properties change drastically with the Oxygen-to-Metal (O/M) ratio. A control technique for O/M ratio was established for measurements of high temperature properties of uranium and plutonium mixed oxide fuels. Sintering behavior, thermal expansion and O/M change of (U{sub 0.7}Pu{sub 0.3})O{sub 2.00} and (U{sub 0.7}Pu{sub 0.3})O{sub 1.99} were investigated in PO{sub 2}-controlled atmosphere which was controlled by H{sub 2}/H{sub 2}O gas system. Sintering behavior changed drastically with O/M ratio, and shrinkage of (U{sub 0.7}Pu{sub 0.3})O{sub 2.00} was faster and more advanced at lower temperatures as compared with (U{sub 0.7}Pu{sub 0.3})O{sub 1.99}. Thermal expansion was observed to be slightly increased with decreasing O/M ratio. (authors)

All space exploration missions traveling beyond Jupiter must use radioisotopic power sources for electrical power. The best isotope to power these sources is plutonium-238. The US supply of Pu-238 is almost exhausted and will be gone within the next decade. The Department of Energy has initiated a production program with a $10M allocation from NASA but the cost is estimated at over $100 M to get to production levels. The Center for Space Nuclear Research has conceived of a potentially better process to produce Pu-238 earlier and for significantly less cost. The new process will also produce dramatically less waste. Potentially, the front end costs could be provided by private industry such that the government only had to pay for the product produced. Under a NASA Phase I NIAC grant, the CSNR has evaluated the feasibility of using a low power, commercially available nuclear reactor to produce at least 1.5 kg of Pu-238 per year. The impact on the neutronics of the reactor have been assessed, the amount of Neptunium target material estimated, and the production rates calculated. In addition, the size of the post-irradiation processing facility has been established. In addition, a new method for fabricating the Pu-238 product into the form used for power sources has been identified to reduce the cost of the final product. In short, the concept appears to be viable, can produce the amount of Pu-238 needed to support the NASA missions, can be available within a few years, and will cost significantly less than the current DOE program.

Time-dependent reduction of PuO2(am) was studied over a range of pH values in the presence of aqueous Fe(II) and magnetite (Fe3O4) nanoparticles. At early time frames (up to 56 days) very little aqueous Pu was mobilized from PuO2(am), even though measured pH and redox potentials, coupled to equilibrium thermodynamic modeling indicated the potential for significant reduction of PuO2(am) to relatively soluble Pu(III). Introduction of Eu(III) or Nd(III) to the suspensions as competitive cations to displace possible sorbed Pu(III) resulted in the release of significant concentrations of aqueous Pu. However, the similarity of aqueous Pu concentrations that resulted from the introduction of Eu(III)/Nd(III) to suspensions with and without magnetite indicated that the Pu was displaced from the PuO2(am), not from magnetite. The fact that soluble forms of Pu can be displaced from the surface of PuO2(am) represents a potential, but previously unidentified, source of Pu to aqueous solution or subsurface groundwaters.

The neutron emission rates from five very pure actinide samples (Th-232, Np-237, Pu-239, Pu-241 and depleted uranium) were measured following equilibrium irradiation in fast and thermal neutron fluxes. The relative abundances (alphas) for the first...

The majority of plutonium presently in the biosphere has come from the testing of nuclear devices. In the early 1950s, the Pu-238/239+240 activity ratio of fallout debris was > 0.04; in the more extensive test series of 1961 to 1962, the Pu-238/239+240 activity ratios were quite consistent at 0.02 to 0.03 and maximum fallout delivery occurred in mid-1963. A significant perturbation in Pu isotope activity ratios occurred in mid-1966 with the deposition of Pu-238 from the SNAP-9A reentry and burn-up. Recently deposited sediments have recorded these events and where accumulation rates are rapid (> 1 cm/y), changes in Pu isotope activity ratios can be used as a geochronological tool.

This paper provides evidence that most of the Pu in the near surface air today is due to resuspension. Vertical and particle size distribution in near surface air over a period of three years were measured. The seasonal variations of Pu in air and the influence of meteorological parameters on these variations are shown. Samples were taken before the Chernobyl accident in an area where only Pu fallout from the atmospheric nuclear tests of the early sixties occurs. The comparison of the behavior of Pu with other trace elements, which were also measured, showed similar behavior of Pu and elements like Ca, Ti and Fe in near surface air. This confirms that most Pu is resuspended because the main source for these elements in air is the soil surface. Resuspension factors and resuspension rate are estimated for all measured elements. A resuspension factor of 0.8 X 10(-8) m-1 and a resuspension rate of 0.09 X 10(-9) s-1 is calculated for Pu.

The objective of this work is to develop and/or apply advanced diagnostics to the understanding of aging of Pu. Advanced characterization techniques such as photoelectron and x-ray absorption spectroscopy will provide fundamental data on the electronic structure of Pu phases. These data are crucial for the validation of the electronic structure methods. The fundamental goal of this project is to narrow the parameter space for the theoretical modeling of Pu aging. The short-term goal is to perform experiments to validate electronic structure calculations of Pu. The long-term goal is to determine the effects of aging upon the electronic structure of Pu. Many of the input parameters for aging models are not directly measurable. These parameters will need to be calculated or estimated. Thus a First Principles-Approach Theory is needed, but it is unclear what terms are important in the Hamiltonian. (H{Psi} = E{Psi}) Therefore, experimental data concerning the 5f electronic structure are needed, to determine which terms in the Hamiltonian are important. The data obtained in this task are crucial for reducing the uncertainty of Task LL-01-developed models and predictions. The data impact the validation of electronic structure methods, the calculation of defect properties, the evaluation of helium diffusion, and the validation of void nucleation models. The importance of these activities increases if difficulties develop with the accelerating aging alloy approach.

Enclosures for confinement of special nuclear materials (SNM) have evolved into the design of gloveboxes. During the early stages of glovebox technology, established practices and process operation requirements defined design criteria. Proven boxes that performed and met or exceeded process requirements in one group or area, often could not be duplicated in other areas or processes, and till achieve the same success. Changes in materials, fabrication and installation methods often only met immediate design criteria. Standardization of design criteria took a big step during creation of ``Special-Nuclear Materials R and D Laboratory Project, Glovebox standards``. The standards defined design criteria for every type of process equipment in its most general form. Los Alamos National Laboratory (LANL) then and now has had great success with Pu-238 processing. However with ever changing Environment Safety and Health (ES and H) requirements and Ta-55 Facility Configuration Management, current design criteria are forced to explore alternative methods of glovebox design fabrication and installation. Pu-238 fuel processing operations in the Power Source Technologies Group have pushed the limitations of current design criteria. More than half of Pu-238 gloveboxes are being retrofitted or replaced to perform the specific fuel process operations. Pu-238 glovebox design criteria are headed toward process designed single use glovebox and supporting line gloveboxes. Gloveboxes that will house equipment and processes will support TA-55 Pu-238 fuel processing needs into the next century and extend glovebox expected design life.

CALPHAD assessment of the thermodynamic properties of a series of Pu-based alloys is briefly presented together with some results on the kinetics of phase formation and transformations in Pu-Ga alloys.

Soil in an area near Palomares, Spain, was contaminated with plutonium as a result of a mid-air collision of U.S. military aircraft in January 1966. The assessment for potential inhalation dose can be found in Iranzo et al., (1987). Long-term monitoring has been used to evaluate remedial actions (Iranzo et al., 1988) and there are many supporting studies of the Pu contamination at Palomares that have been carried out by the Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT) in Madrid. The purpose of this study is to evaluate the resuspension of Pu from the soil in terms of Pu-concentrations in air and resuspension rates in a complementary investigation to those of CIEMAT but in an intensive short-term field effort. This study complements the resuspension studies of CIEMAT at Palomares with additional information, and with confirmation of their previous studies. Observed mass loadings (M) were an average of 70 mg/m{sup 3} with peaks in the daytime of 130 mg/m{sup 3} and low values at night below 30 {micro}g/m{sup 3}. The Pu-activity of aerosols (A) downwind of plot 2-1 was 0.12 Bq/g and the enhancement factor (E{sub f}) had a value of 0.3, which is low but similar to a typical value of 0.7 for other undisturbed sites. This E{sub f} value may increase further away from ground zero. The particle size distribution of the Pu in air measured by cascade impactors was approximately lognormal with a median aerodynamic diameter of 3.7 {micro}m and a geometric standard deviation of 3.5 in the respirable range. This peak midway between 1 ? m and 10 {micro}m in the respirable range is commonly observed. Daily fluctuations in the Pu concentration in air (C) detected by the UHV were lognormally distributed with a geometric standard deviation of 4.9 indicating that the 98th percentile would be 24 times as high as the median. Downwind of plot 2-1 the mean Pu concentration in air, C, was 8.5 {micro}Bq/m{sup 3}. The resuspension factor (Sf) was 2.4 x 10{sup -10} m{sup -1} and agrees very well with the values between 10{sup -10} m{sup -1} and 10{sup -9} m{sup -1} previously reported. We observed a mean Pu/Am ratio of 7.1 with a relative variation of 30%, which compares well with a mean value of 6.5 for nearby plot 2-2. The resuspension rate (R) was in the middle of the range, 10{sup -11} s{sup -1} to 10{sup -12} s{sup -1} as observed in other stable sites, and indicates low potential for Pu redistribution.

X-ray Absorption Fine Structure Spectroscopy (XAFS) at the Pu L{sub II/III} edge was used to determine the speciation of this element in (1) Hanford Z-9 Pu crib samples, (2) deteriorated waste resins from a chloride process ion-exchange purification line, and (3) the sediments from two Waste Isolation Pilot Plant Liter Scale simulant brine systems. The Pu speciation in all of these samples except one is within the range previously displayed by PuO{sub 2+x-2y}(OH){sub y}{center_dot}zH{sub 2}O compounds, which is expected based on the putative thermodynamic stability of this system for Pu equilibrated with excess H{sub 2}O and O{sub 2} under environmental conditions. The primary exception was a near neutral brine experiment that displayed evidence for partial substitution of the normal O-based ligands with Cl{sup -} and a concomitant expansion of the Pu-Pu distance relative to the much more highly ordered Pu near neighbor shell in PuO{sub 2}. However, although the Pu speciation was not necessarily unusual, the Pu chemistry identified via the history of these samples did exhibit unexpected patterns, the most significant of which may be that the presence of the Pu(V)-oxo species may decrease rather than increase the overall solubility of these compounds. Several additional aspects of the Pu speciation have also not been previously observed in laboratory-based samples. The molecular environmental chemistry of Pu is therefore likely to be more complicated than would be predicted based solely on the behavior of PuO{sub 2} under laboratory conditions.

- 1 - Nuclear magnetic resonance offers new insights into Pu 239 May 29, 2012 Nuclear magnetic signal of plutonium 239's unique nuclear magnetic resonance signature has been detected by scientists on the subject, "Observation of 239 Pu Nuclear Magnetic Resonance," was published in the May 18 issue of Science

This monthly report for /sup 238/Pu Fuel Form Activities has two main sections: SRP-PuFF facility and SRL Fuel Form Activities. The program status, budget information, and milestone schedules are discussed in each main section. The Work Breakdown Structure (WBS) for this program is shown. Only one monthly report per year is processed for EDB.

The purpose or scope of the ASME OM Code is to establish the requirements for pre-service and in-service testing of nuclear power plant components to assess their operational readiness. For MOVs this includes those that perform a specific function in shutting down a reactor to the safe shutdown condition, maintaining the safe shutdown condition, and mitigating the consequences of an accident. This paper will present a brief history of industry and regulatory activities related to MOVs and the development of Code requirements to address weaknesses in earlier versions of the OM Code. The paper will discuss the MOV requirements contained in the 2009 version of ASME OM Code, specifically Mandatory Appendix III and OMN-1, Revision 1.

We present results on the yield of sputtering of Pu atoms from a Pu foil, bombarded by fission fragments from a {sup 252}Cf source in transmission geometry. We have found the number of Pu atoms/incoming fission fragments ejected to be 63 {+-} 1. In addition, we show measurements of the sputtering yield as a function of distance from the central axis, which can be understood as an angular distribution of the yield. The results are quite surprising in light of the fact that the Pu foil is several times the thickness of the range of fission fragment particles in Pu. This indicates that models like the binary collision model are not sufficient to explain this behavior.

Unusual circumstances could result in contact between molten Pu and solid Be components. Since intimate contact between Pu and Be results in an intense neutron source via the ({alpha},n) reaction it is very difficult to study the kinetics of the Pu-Be interaction. The published Pu-Be phase diagram is characterized by a single intermetallic compound, PuBe{sub 13} which exists in equilibrium with all of the Pu allotropes, and two eutectics with no measurable solubility range in any of the solid phases. This pattern is known to be followed by all of the rare earths, and some of the actinides. Although most of these phase diagrams are poorly defined in terms of solubility and the location of the eutectics, all have been characterized to the extent of having a single intermetallic compound with a melting point in excess of 1,500 C. Consequently it seems reasonable that by studying the reactions of these other metals with Be, it should be possible to predict kinetics and mechanisms of the Pu-Be interaction using known physical and thermodynamic properties. The most obvious difference between Pu and potential surrogate elements is in their melting points. This is not the most important consideration however due to the presence of the two eutectics in each of the M-Be systems (where M is used to refer to any of the surrogates). In the last meeting of this series the authors reported the results of studies using Yb as a surrogate for Pu. Here they will discuss the results obtained using Sm and Ce and contrast them with the earlier results as well as with Pu-Be experiments conducted using very similar experimental conditions.

The U.S. Department of Energy has decided to dispose of a portion of its surplus plutonium by reconstituting it into mixed oxide (MOX) fuel and irradiating it in commercial power reactors. As part of fuel qualification, four lead assemblies were manufactured and irradiated to a maximum fuel rod average burnup of 47.3 MWd/kg heavy metal. This was the world s first commercial irradiation of MOX fuel with a 240Pu/239Pu ratio less than 0.10. Five fuel rods with varying burnups and plutonium contents were selected from one of the assemblies and shipped to Oak Ridge National Laboratory for hot cell examination. This paper discusses the results of those examinations with emphasis on cladding performance. Exams relevant to the cladding included visual and eddy current exams, profilometry, microscopy, hydrogen analysis, gallium analysis, and mechanical testing. There was no discernible effect of the type of MOX fuel on the performance of the cladding.

Proceedings ofthe 2003 IEEE lnlernstional Conference om Robotics &Automation Taipei, Taiwan to be a highly effectivemeans to control a robot manipulator through the use of visual data. It provides a high. the end of th31 lnter\\al is leis than the value ot the tuncuo

and resources, and management of project execution followed by earned value analysis. Along the way we1 OM 337.5: Project Management Spring 2014 Instructor: G.J. Gutiérrez Office: CBA 3.422 Phone: 1. As a consequence, the management of projects presents a different set of challenges than the management

I' om Data Mining to Knowledge Discovery: Overview Usama M. Fayyad Jet Propulsion Laboratory knowledge discovery and data ~g. We begin with a definition of the KDD process and basic data mining :=c on the order of 50 giga- bytes of remotely sensed image data per hour when operational in the late 1990s

Despite intense experimental and theoretical work on Pu, there is still little understanding of the strange properties of this metal. We used resonant ultrasound spectroscopy method to investigate the elastic properties of pure polycrystalline Pu at high temperatures. Shear and longitudinal elastic moduli of the {gamma}-phase of Pu were determined simultaneously and the bulk modulus was computed from them. A smooth linear and large decrease of all elastic moduli with increasing temperature was observed. We calculated the Poisson ratio and found that it increases from 0.242 at 519K to 0.252 at 571K.

A Pu(IV) polymer not extractable from a nuclear fuel reclaiming solution by conventional processes is electrolytically converted to Pu.sup.3+ and PuO.sub.2.sup.2+ ions which are subsequently converted to Pu.sup.4+ ions extractable by the conventional processes.

In the 1980s, measurements of the cumulative $\\beta$ spectra of the fission products following the thermal neutron induced fission of $^{235}$U, $^{239}$Pu, and $^{241}$Pu were performed at the magnetic spectrometer BILL at the ILL in Grenoble. This data was published in bins of 250 keV. In this paper, we re-publish the original data in a binning of 50 keV for $^{235}$U and 100 keV for $^{239}$Pu and $^{241}$Pu.

The proposed neutron capture measurement for {sup 238}Pu was carried out in Nov-Dec, 2010, using the DANCE array at LANSCE, LANL. The total beam-on-target time is about 14 days plus additional 5 days for the background measurement. The target was prepared at LLNL with the new electrplating cell capable of plating the {sup 238}Pu isotope simultaneously on both sides of the 3-{micro}m thick Ti backing foil. A total mass of 395 {micro}g with an activity of 6.8 mCi was deposited onto the area of 7 mm in diameter. The {sup 238}Pu sample was enriched to 99.35%. The target was covered by 1.4 {micro}m double-side aluminized mylar and then inserted into a specially designed vacuum-tight container, shown in Fig. 1, for the {sup 238}Pu containment. The container was tested for leaks in the vacuum chamber at LLNL. An identical container without {sup 238}Pu was made as well and used as a blank for the background measurement.

Concentrations of /sup 239 + 240/Pu are reported in tissues of several species of reef and pelagic fish caught at 14 different atolls in the northern Marshall Islands. Several regularities that are species dependent are evident in the distribution of /sup 239 + 240/Pu among different body tissues. Concentrations in liver always exceeded those in bone and concentrations were lowest in the muscle of all fish analyzed. A progressive discrimination against /sup 239 + 240/Pu was observed at successive trophic levels at all atolls except Bikini and Enewetak, where it was difficult to conclude if any real difference exists between the average concentration factor for /sup 239 + 240/Pu among all fish, which include bottom feeding and grazing herbivores, bottom feeding carnivores, and pelagic carnivores from different atoll locations. The average concentration of /sup 239 + 240/Pu in the muscle of surgeonfish from Bikini and Enewetak was not significantly different from the average concentrations determined in these fish at the other, lesser contaminated atolls. Concentrations among all 3rd, 4th, and 5th trophic level species are highest at Bikini where higher environmental concentrations are found. The reasons for the anomalously low concentrations in herbivores from Bikini and Enewetak are not known.

This guide, sponsored by DOE's Federal Energy Management Program, highlights operations and maintenance (O&M) programs targeting energy efficiency that are estimated to save 5% to 20% on energy bills without a significant capital investment. The purpose of this guide is to provide the federal O&M energy manager and practitioner with useful information about O&M management, technologies, energy efficiency and cost-reduction approaches.

This paper summarizes efforts leading to selection of a new fluid for the determination of the density of large Pu parts. Based on an extended literature search, perfluorotributylamine (FC-43) was chosen for an experimental study. Plutonium coupon corrosion studies were performed by exposing Pu to deaerated and aerated solutions and measuring corrosion gravimetrically. Corrosion rates were determined. Samples of deaerated and aerated perfuluorotributylamine (FC-43) were also irradiated with {sup 60}Co gamma rays (96 Gy/min) to various doses. The samples were extracted with NaOH and analyzed by IC and showed the presence of F and Cl{sup -}. The G-values were established. In surface study experiments Pu coupons were exposed to deaerated and aerated solutions of FC-43 and analyzed by X-ray photoelectron spectroscopy (XPS). The XPS data indicate that there is no detectable surface effect caused by the new fluid. In conclusion the FC-43 was determined to be a very effective and practical fluid for Pu density measurements.

Plutonium and plutonium-based alloys containing Al or Ga exhibit numerous phases with crystal structures ranging from simple monoclinic to face-centered cubic. Only recently, however, has there been increased convergence in the actinides community on the details of the equilibrium form of the phase diagrams. Practically speaking, while the phase diagrams that represent the stability of the fcc {delta}-phase field at room temperature are generally applicable, it is also recognized that Pu and its alloys are never truly in thermodynamic equilibrium because of self-irradiation effects, primarily from the alpha decay of Pu isotopes. This article covers past and current research on several properties of Pu and Pu-(Al or Ga) alloys and their connections to the crystal structure and the microstructure. We review the consequences of radioactive decay, the recent advances in understanding the electronic structure, the current research on phase transformations and their relations to phase diagrams and phase stability, the nature of the isothermal martensitic {delta} {yields} {alpha}{prime} transformation, and the pressure-induced transformations in the {delta}-phase alloys. New data are also presented on the structures and phase transformations observed in these materials following the application of pressure, including the formation of transition phases.

, and a graphite-moderated counting system were constructed to perform all these experiments. The calculated values for the five-group U-235 delayed neutron parameters and the six-group Pu-239 delayed neutron parameters were compared with the values...

in the counting station. A set of highly purified actinide samples (U-235 and Pu-239) was irradiated in these experiments by using the Texas A&M University Nuclear Science Center Reactor. A fast pneumatic transfer system, an integrated computer control system...

) in July 2008 and January 2009. These measurements successfully showed that it is possible to measure the Pu x-ray peak at 103.7 keV in PWR spent fuel (~1 percent Pu) using a planar HPGe detector. Prior to these measurement campaigns, the Pu peak has only...

1 Staff summary of Issues and Recommendations Long Term O&M Contingency Plans *Preliminary draft. Overview The majority the recommendations received by the Council regarding long term O&M/contingency plans)to ensure long-term funding of O&M (35) 3. Fish Screens and Fishways a. The habitat based Program relies

Hosted by the Federal Energy Management Program (FEMP), this seminar covers operations and maintenance (O&M) best practices for photovoltaic (PV) systems of 100 kilowatt or less, including planning for a PV O&M scope of work and maintenance procedures to keep the system operating at optimal capacity.

i MODEL MOA ACCEPTANCE OF CONTRIBUTED FUNDS (33 U.S.C. 701h) FOR O&M DREDGING WHERE SUCH DREDGING be used for O&M dredging that is a Federal expense; there is enough Federal funds for Corps to award a reasonable dredging contract; and the Contributor provides a specified amount to allow additional O

The Milliwatt Radioisotopic Thermoelectric Generator (RTG) provides power for permissive-action links. These nuclear batteries convert thermal energy to electrical energy using a doped silicon-germanium thermopile. The thermal energy is provided by a heat source made of {sup 238}Pu, in the form of {sup 238}PuO{sub 2} granules. The granules are contained in 3 layers of encapsulation. A thin T-111 liner surrounds the {sup 238}PuO{sub 2} granules and protects the second layer (strength member) from exposure to the fuel granules. The T-111 strength member contains the fuel under impact condition. An outer clad of Hastelloy-C protects the T-111 from oxygen embrittlement. The T-111 strength member is considered the critical component in this {sup 238}PuO{sub 2} containment system. Any compromise in the strength member is something that needs to be characterized. Consequently, the T-111 strength member is characterized upon it's decommissioning through Scanning Electron Microscopy (SEM), and Metallography. SEM is used in Secondary Electron mode to reveal possible grain boundary deformation and/or cracking in the region of the strength member weld. Deformation and cracking uncovered by SEM are further characterized by Metallography. Metallography sections are mounted and polished, observed using optical microscopy, then documented in the form of photomicrographs. SEM may further be used to examine polished Metallography mounts to characterize elements using the SEM mode of Energy Dispersive X-ray Spectroscopy (EDS). This paper describes the characterization of the metallurgical condition of decommissioned RTG heat sources.

As part of a large Pu disposition program, a zirconolite-rich titanate ceramic is being developed at Lawrence Livermore National Laboratory (LLNL) as a possible immobilization material. This same material is being tested at Argonne National Laboratory (ANL). The goal of this study is to describe the corrosion behavior of this ceramic, particularly the release of Pu and Gd, using results from several static corrosion tests (MCC-1, PCT-A, and PCT-B). The release of relatively large amounts of Al, Ba, and Ca in short-term tests (3 day MCC-1 and 7 day PCT-A) indicates that these elements are released from grain boundaries or from highly soluble phases. Results from long-term (28, 98, and 182 day) PCT-B show that the releases of Al, Ba, and Ca decrease with time, the releases of U and Zr increase with time, and that the releases of Cs, Gd, Mo, and Pu remain fairly constant. Formation of alteration phases may lead to the decrease of Ba and Ca in leachate solutions. Due to the heterogeneous nature of the material, the formation of alteration phases, and the inherently low solubility of several elements, no element(s) could be recommended as good markers for the overall corrosion of this ceramic. Data show that, due to the complex nature of this material, the release of each element should be considered separately.

In support of the Alternate Feed Stock Two (AFS-2) PuO{sub 2} production campaign, Savannah River National Laboratory (SRNL) conducted a series of experiments concluding that dissolving Pu metal at 95°C using a 6–10 M HNO{sub 3} solution containing 0.05–0.2 M KF and 0–2 g/L B could reduce the oxidation of Pu(IV) to Pu(VI) as compared to dissolving Pu metal under the same conditions but at or near the boiling temperature. This flowsheet was demonstrated by conducting Pu metal dissolutions at 95°C to ensure that PuO{sub 2} solids were not formed during the dissolution. These dissolution parameters can be used for dissolving both Aqueous Polishing (AP) and MOX Process (MP) specification materials. Preceding the studies reported herein, two batches of Pu metal were dissolved in the H-Canyon 6.1D dissolver to prepare feed solution for the AFS-2 PuO{sub 2} production campaign. While in storage, UV-visible spectra obtained from an at-line spectrophotometer indicated the presence of Pu(VI). Analysis of the solutions also showed the presence of Fe, Ni, and Cr. Oxidation of Pu(IV) produced during metal dissolution to Pu(VI) is a concern for anion exchange purification. Anion exchange requires Pu in the +4 oxidation state for formation of the anionic plutonium(IV) hexanitrato complex which absorbs onto the resin. The presence of Pu(VI) in the anion feed solution would require a valence adjustment step to prevent losses. In addition, the presence of Cr(VI) would result in absorption of chromate ion onto the resin and could limit the purification of Pu from Cr which may challenge the purity specification of the final PuO{sub 2} product. Initial experiments were performed to quantify the rate of oxidation of Pu(IV) to Pu(VI) (presumed to be facilitated by Cr(VI)) as functions of the HNO{sub 3} concentration and temperature in simulated dissolution solutions containing Cr, Fe, and Ni. In these simulated Pu dissolutions studies, lowering the temperature from near boiling to 95 °C reduced the oxidation rate of Pu(IV) to Pu(VI). For 8.1 M HNO{sub 3} simulated dissolution solutions, at near boiling conditions >35% Pu(VI) was present in 50 h while at 95 °C <10% Pu(VI) was present at 50 h. At near boiling temperatures, eliminating the presence of Cr and varying the HNO{sub 3} concentration in the range of 7–8.5 M had little effect on the rate of conversion of Pu(IV) to Pu(VI). HNO{sub 3} oxidation of Pu(IV) to Pu(VI) in a pure solution has been reported previously. Based on simulated dissolution experiments, this study concluded that dissolving Pu metal at 95°C using a 6 to 10 M HNO{sub 3} solution 0.05–0.2 M KF and 0–2 g/L B could reduce the rate of oxidation of Pu(IV) to Pu(VI) as compared to near boiling conditions. To demonstrate this flowsheet, two small-scale experiments were performed dissolving Pu metal up to 6.75 g/L. No Pu-containing residues were observed in the solutions after cooling. Using Pu metal dissolution rates measured during the experiments and a correlation developed by Holcomb, the time required to completely dissolve a batch of Pu metal in an H-Canyon dissolver using this flowsheet was estimated to require nearly 5 days (120 h). This value is reasonably consistent with an estimate based on the Batch 2 and 3 dissolution times in the 6.1D dissolver and Pu metal dissolution rates measured in this study and by Rudisill et al. Data from the present and previous studies show that the Pu metal dissolution rate decreases by a factor of approximately two when the temperature decreased from boiling (112 to 116°C) to 95°C. Therefore, the time required to dissolve a batch of Pu metal in an H-Canyon dissolver at 95°C would likely double (from 36 to 54 h) and require 72 to 108 h depending on the surface area of the Pu metal. Based on the experimental studies, a Pu metal dissolution flowsheet utilizing 6–10 M HNO{sub 3} containing 0.05–0.2 M KF (with 0–2 g/L B) at 95°C is recommended to reduce the oxidation of Pu(IV) to Pu(VI) as compared to near boiling conditions. The time required to completely di

In order to obtain the resonance parameters in a single energy range and the corresponding covariance matrix, a reevaluation of 239Pu was performed with the code SAMMY. The most recent experimental data were analyzed or reanalyzed in the energy range thermal to 2.5 keV. The normalization of the fission cross section data was reconsidered by taking into account the most recent measurements of Weston et al. and Wagemans et al. A full resonance parameter covariance matrix was generated. The method used to obtain realistic uncertainties on the average cross section calculated by SAMMY or other processing codes was examined.

Density-functional electronic-structure calculations have been used to investigate the ambient pressure and low temperature elastic properties of the ground-state {alpha} phase of plutonium metal. The electronic structure and correlation effects are modeled within a fully relativistic antiferromagnetic treatment with a generalized gradient approximation for the electron exchange and correlation functional. The 13 independent elastic constants, for the monoclinic {alpha}-Pu system, are calculated for the observed geometry. A comparison of the results with measured data from recent resonant ultrasound spectroscopy for a cast sample is made.

Density-functional electronic structure calculations have been used to investigate the ambient pressure and low temperature elastic properties of the ground-state {alpha} phase of plutonium metal. The electronic structure and correlation effects are modeled within a fully relativistic anti-ferromagnetic treatment with a generalized gradient approximation for the electron exchange and correlation functionals. The 13 independent elastic constants, for the monoclinic {alpha}-Pu system, are calculated for the observed geometry. A comparison of the results with measured data from resonant ultrasound spectroscopy for a cast sample is made.

In this document the results of neutronics studies of <<100%Pu>> MOX LTA design are presented. The parametric studies of infinite MOX-UOX grids, MOX-UOX core fragments and of VVER-1000 core with 3 MOX LTAs are performed. The neutronics parameters of MOX fueled core have been performed for the chosen design MOX LTA using the Russian 3D code BIPR-7A and 2D code PERMAK-A with the constants prepared by the cell spectrum code TVS-M.

Co-processing process, which is the modified Purex process focused on co-recovery of Pu and U, has been studied at Operation Testing Laboratory, Tokai Reprocessing Plant in JAEA. The set up of the process was performed with flow-sheets study by process calculation to avoid Pu isolation in the whole process and to co-recover Pu/U product solution with a suitable Pu/U ratio (0.5< Pu/U <2). The initial Pu/U ratios of the feed solutions were taken as 1%, 3% and 20% considering the composition of the future spent fuels. The verification of the flow-sheets for each feed solutions were carried out with mixer-setters and active Pu/U feed solutions, focusing on the partitioning unit, and favorable back extraction performances of Pu accompanied by U were observed at all cases of the given feed solutions. According to these results, the co-processing process showed a good prospect to treat all kinds of future fuels from LWR, LWR-MOX and FBR, and a good prospect to be simplified by omitting the Pu/U purification cycle.

The Zero Power Physics Reactor (ZPPR) operated from April 18, 1969, until 1990. ZPPR operated at low power for testing nuclear reactor designs. This paper examines the temperature of Pu content ZPPR fuel while it is in storage. Heat is generated in the fuel due to Pu and Am decay and is a concern for possible cladding damage. Damage to the cladding could lead to fuel hydriding and oxidizing. A series of computer simulations were made to determine the range of temperatures potentially occuring in the ZPPR fuel. The maximum calculated fuel temperature is 292°C (558°F). Conservative assumptions in themore »model intentionally overestimate temperatures. The stored fuel temperatures are dependent on the distribution of fuel in the surrounding storage compartments, the heat generation rate of the fuel, and the orientation of fuel. Direct fuel temperatures could not be measured but storage bin doors, storage sleeve doors, and storage canister temperatures were measured. Comparison of these three temperatures to the calculations indicates that the temperatures calculated with conservative assumptions are, as expected, higher than the actual temperatures. The maximum calculated fuel temperature with the most conservative assumptions is significantly below the fuel failure criterion of 600°C (1,112°F).« less

ZPR-6 Assembly 7 (ZPR-6/7) encompasses a series of experiments performed at the ZPR-6 facility at Argonne National Laboratory in 1970 and 1971 as part of the Demonstration Reactor Benchmark Program (Reference 1). Assembly 7 simulated a large sodium-cooled LMFBR with mixed oxide fuel, depleted uranium radial and axial blankets, and a core H/D near unity. ZPR-6/7 was designed to test fast reactor physics data and methods, so configurations in the Assembly 7 program were as simple as possible in terms of geometry and composition. ZPR-6/7 had a very uniform core assembled from small plates of depleted uranium, sodium, iron oxide, U{sub 3}O{sub 8} and Pu-U-Mo alloy loaded into stainless steel drawers. The steel drawers were placed in square stainless steel tubes in the two halves of a split table machine. ZPR-6/7 had a simple, symmetric core unit cell whose neutronic characteristics were dominated by plutonium and {sup 238}U. The core was surrounded by thick radial and axial regions of depleted uranium to simulate radial and axial blankets and to isolate the core from the surrounding room. The ZPR-6/7 program encompassed 139 separate core loadings which include the initial approach to critical and all subsequent core loading changes required to perform specific experiments and measurements. In this context a loading refers to a particular configuration of fueled drawers, radial blanket drawers and experimental equipment (if present) in the matrix of steel tubes. Two principal core configurations were established. The uniform core (Loadings 1-84) had a relatively uniform core composition. The high {sup 240}Pu core (Loadings 85-139) was a variant on the uniform core. The plutonium in the Pu-U-Mo fuel plates in the uniform core contains 11% {sup 240}Pu. In the high {sup 240}Pu core, all Pu-U-Mo plates in the inner core region (central 61 matrix locations per half of the split table machine) were replaced by Pu-U-Mo plates containing 27% {sup 240}Pu in the plutonium component to construct a central core zone with a composition closer to that in an LMFBR core with high burnup. The high {sup 240}Pu configuration was constructed for two reasons. First, the composition of the high {sup 240}Pu zone more closely matched the composition of LMFBR cores anticipated in design work in 1970. Second, comparison of measurements in the ZPR-6/7 uniform core with corresponding measurements in the high {sup 240}Pu zone provided an assessment of some of the effects of long-term {sup 240}Pu buildup in LMFBR cores. The uniform core version of ZPR-6/7 is evaluated in ZPR-LMFR-EXP-001. This document only addresses measurements in the high {sup 240}Pu core version of ZPR-6/7. Many types of measurements were performed as part of the ZPR-6/7 program. Measurements of criticality, sodium void worth, control rod worth and reaction rate distributions in the high {sup 240}Pu core configuration are evaluated here. For each category of measurements, the uncertainties are evaluated, and benchmark model data are provided.

The quantification of plutonium (Pu) in spent nuclear fuel is an increasingly important safeguards issue. There exists an estimated worldwide 980 metric tons of Pu in the nuclear fuel cycle and the majority is in spent nuclear fuel waiting for long...

It is desirable to realize topological phases in artificial structures by engineering electronic band structures. In this paper we investigate (PbTe)[subscript m](SnTe)[subscript 2n?m] superlattices along the [001] direction ...

As a result of treaty agreements between Russia and the US, portions of their respective plutonium and nuclear weapons stockpiles have been declared excess. In support of the US Department of Energy's 1998 decision to pursue immobilization of a portion of the remaining Pu in a titanate-based ceramic, the authors prepared nearly 200 radiation-damage test specimens of five Pu- and {sup 238}Pu-ceramics containing 10 mass% Pu to determine the effects of irradiation from the contained Pu and U on the ceramic. The five Pu-ceramics were (1) phase-pure pyrochlore [ideally, Ca(U, Pu)Ti{sub 2}O{sub 7}], (2) pyrochlore-rich baseline, (3) pyrochlore-rich baseline with impurities, (4) phase-pure zirconolite [ideally Ca(U, Pu)Ti{sub 2}O{sub 7}], and (5) a zirconolite-rich baseline. These ceramics were prepared with either normal weapons-grade Pu, which is predominantly {sup 239}Pu, or {sup 238}Pu. The {sup 238}Pu accelerates the radiation damage relative to the {sup 239}Pu because of its much higher specific activity. The authors were unsuccessful in preparing phase-pure (Pu, U) brannerite, which is the third crystalline phase present in the baseline immobilization form. Since these materials will contain {approximately}10 mass% Pu and about 20 mass% U, radiation damage to the crystalline structure of these materials will occur overtime. As the material becomes damaged from the decay of the Pu and U, it is possible for the material to swell as both the alpha particles and recoiling atoms rupture chemical bonds within the solid. As the material changes density, cracking, perhaps in the form of microcracks, may occur. If cracking occurs in ceramic that has been placed in a repository, the calculated rate of radionuclide release if the can has corroded would increase proportionately to the increase in surface area. To investigate the effects of radiation damage on the five ceramics prepared, the authors are storing the specimens at 20, 125, and 250 C until the {sup 238}Pu specimens become metamict and the damage saturates. They will characterize and test these specimens every 6 months by (1) monitoring the dimensions, (2) monitoring the geometric and pycnometric densities, (3) monitoring the appearance, (4) determining the normalized amount leached during a 3-day, static, 90 C leach test in high purity water, and (5) monitoring the crystal structure with x-ray diffraction crystallography (XRD). In this paper, the authors document the preparation and initial characterization of the materials that were made in this study. The initial XRD characterizations indicate that the phase assemblages appear to be correct with the exception of the {sup 238}Pu-zirconolite baseline material. They made this latter material using too much Pu, so this material contains unreacted PuO{sub 2}. The characterization of the physical properties of these materials found that the densities for all but three materials appear to be > 94% of theoretical, and only a few of the specimens have significant cracking. Those with cracking were the {sup 239}Pu-zirconolite specimens, which were sintered with a heat-up rate of 5 C/min. They sintered the {sup 238}Pu-zirconolite specimens with a heat-up rate of 2.5 C/min and obtained specimens with only minor surface cracking. Elemental releases during the 3-day MCC leach tests show that the normalized elemental releases depend on (1) whether the Pu is {sup 239}Pu or {sup 238}Pu, (2) the material type, and (3) the identity of the constituent. The effect of the Pu isotope in the ceramic is most dramatic for Pu release, with nominally 50 to 100 times more Pu activity released from the {sup 238}Pu specimens. This is unlikely to be an early indicator of radiation damage, because of the short time between specimen preparation and testing. In contrast greater amounts of Mo are released from the {sup 239}Pu specimens. Of the contained constituents, Ca Al, Pu, and U are the species found at relatively higher levels in the leachates.

This document contains the agenda and meeting notes. Topics of discussion included US Pu disposition ceramics activities, Russian experience and proposals in Pu ceramics, and development of possible Russian ceramic proposals or collaborations.

In this annual report we illustrate the methodology of the consistent data assimilation that allows to use the information coming from integral experiments for improving the basic nuclear parameters used in cross section evaluation. A series of integral experiments are analyzed using the EMPIRE evaluated files for 242Pu and 105Pd. In particular irradiation experiments (PROFIL-1 and -2, TRAPU-1, -2 and -3) provide information about capture cross sections, and a critical configuration, COSMO, where fission spectral indexes were measured, provides information about fission cross section. The observed discrepancies between calculated and experimental results are used in conjunction with the computed sensitivity coefficients and covariance matrix for nuclear parameters in a consistent data assimilation. The results obtained by the consistent data assimilation indicate that not so large modifications on some key identified nuclear parameters allow to obtain reasonable C/E. However, for some parameters such variations are outside the range of 1 s of their initial standard deviation. This can indicate a possible conflict between differential measurements (used to calculate the initial standard deviations) and the integral measurements used in the statistical data adjustment. Moreover, an inconsistency between the C/E of two sets of irradiation experiments (PROFIL and TRAPU) is observed for 242Pu. This is the end of this project funded by the Nuclear Physics Program of the DOE Office of Science. We can indicate that a proof of principle has been demonstrated for a few isotopes for this innovative methodology. However, we are still far from having explored all the possibilities and made this methodology to be considered proved and robust. In particular many issues are worth further investigation: • Non-linear effects • Flexibility of nuclear parameters in describing cross sections • Multi-isotope consistent assimilation • Consistency between differential and integral experiments

by 88 Watts per fixture if two lamps and a ballast are disconnected. In addition, a formal program of turning-off lights in corridors and elevator lobbies after hours would contribute to less energy consumption. Texas State Energy Conservation Office...ESL-TR-93/10-03 LoanSTAR Monitoring and Analysis Program Summary of UTMB O&M Project: ENERGY CONSERVATION POTENTIAL IN FIVE BUILDINGS Submitted to the Texas State Energy Conservation Office By the Monitoring and Analysis Task E (O&M) Dr. Mingsheng...

Over a period of 30 years more than a hundred Zero Power Reactor (ZPR) critical assemblies were constructed at Argonne National Laboratory. The ZPR facilities, ZPR-3, ZPR-6, ZPR-9 and ZPPR, were all fast critical assembly facilities. The ZPR critical assemblies were constructed to support fast reactor development, but data from some of these assemblies are also well suited to form the basis for criticality safety benchmarks. Of the three classes of ZPR assemblies, engineering mockups, engineering benchmarks and physics benchmarks, the last group tends to be most useful for criticality safety. Because physics benchmarks were designed to test fast reactor physics data and methods, they were as simple as possible in geometry and composition. The principal fissile species was {sup 235}U or {sup 239}Pu. Fuel enrichments ranged from 9% to 95%. Often there were only one or two main core diluent materials, such as aluminum, graphite, iron, sodium or stainless steel. The cores were reflected (and insulated from room return effects) by one or two layers of materials such as depleted uranium, lead or stainless steel. Despite their more complex nature, a small number of assemblies from the other two classes would make useful criticality safety benchmarks because they have features related to criticality safety issues, such as reflection by soil-like material. The term 'benchmark' in a ZPR program connotes a particularly simple loading aimed at gaining basic reactor physics insight, as opposed to studying a reactor design. In fact, the ZPR-6/7 Benchmark Assembly (Reference 1) had a very simple core unit cell assembled from plates of depleted uranium, sodium, iron oxide, U3O8, and plutonium. The ZPR-6/7 core cell-average composition is typical of the interior region of liquid-metal fast breeder reactors (LMFBRs) of the era. It was one part of the Demonstration Reactor Benchmark Program,a which provided integral experiments characterizing the important features of demonstration-size LMFBRs. As a benchmark, ZPR-6/7 was devoid of many 'real' reactor features, such as simulated control rods and multiple enrichment zones, in its reference form. Those kinds of features were investigated experimentally in variants of the reference ZPR-6/7 or in other critical assemblies in the Demonstration Reactor Benchmark Program.

A new method that allows rapid preconcentration and separation of plutonium and neptunium in water samples was developed for the measurement of {sup 237}Np and Pu isotopes by inductively-coupled plasma mass spectrometry (ICP-MS) and alpha spectrometry; a hybrid approach. {sup 238}U can interfere with {sup 239}Pu measurement by ICP-MS as {sup 238}UH{sup +} mass overlap and {sup 237}Np via peak tailing. The method provide enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then moving Pu to DGA resin for additional removal of uranium. The decontamination factor for uranium from Pu is almost 100,000 and the decontamination factor for U from Np is greater than 10,000. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration is performed using a streamlined calcium phosphate precipitation method. Purified solutions are split between ICP-MS and alpha spectrometry so that long and short-lived Pu isotopes can be measured successfully. The method allows for simultaneous extraction of 20 samples (including QC samples) in 4 to 6 hours, and can also be used for emergency response. {sup 239}Pu, {sup 242}Pu and {sup 237}Np were measured by ICP-MS, while {sup 236}Pu, {sup 238}Pu, and {sup 239}Pu were measured by alpha spectrometry.

A Weibull distribution was fit to the osteosarcoma death times of beagles given single intravenous injections of /sup 239/Pu. For injected doses in the range 0-1..mu..Ci/kg the osteosarcoma incidence rate h(t) at t days after injection can be fit by a quadratic function of injected dose d: h(t) = 2.61 X 10/sup -18/ d/sup 2/t/sup 4.91/. The best-fitting linear function was rejected by the data (P < 0.001). A different formula for h(t), derived from a multistage theory for osteosarcoma induction, was also fit to these data. For this purpose microdosimetry calculations were used to estimate the dose to the cells at risk in the endosteal layer (endosteal dose). According to the best fit, h(t) is a quadratic function of endosteal dose at low doses. A linear dose-response relationship was again rejected. The absence of a linear component at low doses might be explained by the fact that 108 of the 185 animals injected at the lowest doses (<0.02 ..mu..Ci/kg) were still alive at the time these data were collected.

Lindstr\\"om theorems characterize logics in terms of model-theoretic conditions such as Compactness and the L\\"owenheim-Skolem property. Most existing characterizations of this kind concern extensions of first-order logic. But on the other hand, many logics relevant to computer science are fragments or extensions of fragments of first-order logic, e.g., k-variable logics and various modal logics. Finding Lindstr\\"om theorems for these languages can be challenging, as most known techniques rely on coding arguments that seem to require the full expressive power of first-order logic. In this paper, we provide Lindstr\\"om theorems for several fragments of first-order logic, including the k-variable fragments for k>2, Tarski's relation algebra, graded modal logic, and the binary guarded fragment. We use two different proof techniques. One is a modification of the original Lindstr\\"om proof. The other involves the modal concepts of bisimulation, tree unraveling, and finite depth. Our results also imply semantic pre...

MODEL MOA ACCEPTANCE OF CONTRIBUTED FUNDS (33 U.S.C. 701h) FOR O&M DREDGING WHERE SUCH DREDGING&M dredging that is a Federal expense; there are no Federal funds available; and the Contributor provides ALL funds needed to perform the dredging and related activities (engineering and design work, environmental

Advanced small modular reactors (AdvSMRs) can contribute to safe, sustainable, and carbon-neutral energy production. The economics of small reactors (including AdvSMRs) will be impacted by the reduced economy-of-scale savings when compared to traditional light water reactors. The most significant controllable element of the day-to-day costs involves operations and maintenance (O&M). Enhancing affordability of AdvSMRs through technologies that help control O&M costs will be critical to ensuring their practicality for wider deployment.A significant component of O&M costs is the management and mitigation of degradation of components due to their impact on planning maintenance activities and staffing levels. Technologies that help characterize real-time risk of failure of key components are important in this context. Given the possibility of frequently changing AdvSMR plant configurations, approaches are needed to integrate three elements – advanced plant configuration information, equipment condition information, and risk monitors – to provide a measure of risk that is customized for each AdvSMR unit and support real-time decisions on O&M. This article describes an overview of ongoing research into diagnostics/prognostics and enhanced predictive risk monitors (ERM) for this purpose.

A new method for the determination of {sup 237}Np and Pu isotopes in large soil samples has been developed that provides enhanced uranium removal to facilitate assay by inductively coupled plasma mass spectrometry (ICP-MS). This method allows rapid preconcentration and separation of plutonium and neptunium in large soil samples for the measurement of {sup 237}Np and Pu isotopes by ICP-MS. {sup 238}U can interfere with {sup 239}Pu measurement by ICP-MS as {sup 238}UH{sup +} mass overlap and {sup 237}Np via {sup 238}U peak tailing. The method provides enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then transferring Pu to DGA resin for additional purification. The decontamination factor for removal of uranium from plutonium for this method is greater than 1 x 10{sup 6}. Alpha spectrometry can also be applied so that the shorter-lived {sup 238}Pu isotope can be measured successfully. {sup 239}Pu, {sup 242}Pu and {sup 237}Np were measured by ICP-MS, while {sup 236}Pu and {sup 238}Pu were measured by alpha spectrometry.

This paper estimates the temperature of high Pu content ZPPR fuel while in storage to determine the probablilty of fuel damage during storage. The Zero Power Physics Reactor (ZPPR) is an experimental reactor which has been decomissioned. It ran only at extremely low power, for testing nuclear reactor designs and was operated as a criticality facility from April 18, 1969 until decommissioned in 1990. Its fuel was manufactured in 1967 and has been in storage since the reactor was decomissioned. Heat is generated in the fuel due to Pu and Am decay and is a concern for possible fuel damage. Any damage to the cladding would be expected to lead to the fuel hydriding and oxidizing over a long period of storage as was described in the analysis of the damage to the ZPPR uranium fuel resulting in the fuel becoming unuseable and a large potential source of contamination. (Ref. Solbrig, 1994). A series of computer runs were made to scope out the range of temperatures that can occur in the ZPPR fuel in storage. The maximum calculated conservative fuel temperature is high (292 degrees C [558 degrees F]) in spite of the fact that the fuel element heat generation rates seem quite low, between 35 and 10 W for containers (called clamshells) full of fuel. However, the ZPPR storage bins, built for safeguards, are very effective insulators. The calculated clamshells and the cavity doors temperatures are also high. No record exists of people receiving skin burns by touching the cavity doors or clamshells, which indicates the computed temperatures may be higher than actual. (Note, gloves are worn when handling hotter clamshells.) Given the high calculated temperatures, a cursory measurement program was conducted to calibrate the calculated results. The measurement of bin doors, cavity doors, and clamshell temperatures would be easy to make if it were not for regulations resulting from security and potential contamination. Due to conservative assumptions in the model like high heat transfer contact resistance between contact surfaces (such as between the fuel and the clamshell), the calculated temperatures are intended to be overestimated. The temperatures of the stored fuel in a particular clamshell are dependent, among other parameters, on the distribution of fuel in the surrounding storage compartments, the heat generation rate of the fuel, and the orientation of fuel in the clamshell (parallel or perpendicular to the door). The distribution of fuel in this analysis was selected to give higher temperatures than actual distributions might give. Due to possible contamination and security concerns, fuel temperatures could not be measured but the bin doors, storage sleeve doors, and clamshell temperatures could be and were measured. The comparison of these three temperatures to the calculations indicates that the temperatures calculated with conservative assumptions are higher than the actual temperatures. This implies that the calculated fuel temperatures are higher than actual also. The maximum calculated fuel temperature with the most conservative assumptions (292 degrees C, (558 degrees F)) is significantly below the no fuel failure criterion of 600 degrees C (1,112 degrees F). Some fuel failures have occurred but these results indicate that the failures are not due to high temperatures encountered in fuel storage.

Abstract Heterogeneous reduction of actinides in higher and more soluble oxidation states to lower more insoluble oxidation states by reductants such as Fe(II) has been the subject of intensive study for more than two decades. However, Fe(II)-induced reduction of sparingly soluble Pu(IV) to the more soluble lower oxidation state Pu(III) has been much less studied even though such reactions can potentially increase the mobility of Pu in the subsurface. Thermodynamic calculations are presented that show how differences in the free energy of various possible solid-phase Fe(III) reaction products can greatly influence aqueous Pu(III) concentrations resulting from reduction of PuO2(am) by Fe(II). We present the first experimental evidence that reduction of PuO2(am) to Pu(III) by Fe(II) was enhanced when the Fe(III) mineral goethite was spiked into the reaction. The effect of goethite on reduction of Pu(IV) was demonstrated by measuring the time-dependence of total aqueous Pu concentration, its oxidation state, and system pe/pH. We also re-evaluated established protocols for determining Pu(III) [(Pu(III) + Pu(IV)) - Pu(IV)] by using thenoyltrifluoroacetone (TTA) in toluene extractions; the study showed that it is important to eliminate dissolved oxygen from the TTA solutions for accurate determinations. More broadly, this study highlights the importance of the Fe(III) reaction product in actinide reduction rate and extent by Fe(II).

Phases and microstructures in the matrix of an as-cast U-Pu-Zr alloy with 3 wt% Am, 2% Np, and 8% rare-earth elements were characterized by scanning and transmission electron microscopy. The matrix consists primarily of two phases, both of which contain Am: ?-(U, Np, Pu, Am) (~70 at% U, 5% Np, 14% Pu, 1% Am, and 10% Zr) and ?-(U, Np, Pu, Am)Zr2 (~25% U, 2% Np, 10-15% Pu, 1-2% Am, and 55-60 at% Zr). These phases are similar to those in U-Pu-Zr alloys, although the Zr content in ?-(U, Np, Pu, Am) is higher than that in ?-(U, Pu) and the Zr content in ?-(U, Np, Pu, Am)Zr2 is lower than that in ?-UZr2. Nanocrystalline actinide oxides with structures similar to UO2 occurred in some areas, but may have formed by reactions with the atmosphere during sample handling. Planar features consisting of a central zone of ?-(U, Np, Pu, Am) bracketed by zones of ?-(U, Np, Pu, Am)Zr2 bound irregular polygons ranging in size from a few micrometers to a few tens of micrometers across. The rest of the matrix consists of elongated domains of ?-(U, Np, Pu, Am) and ?-(U, Np, Pu, Am)Zr2. Each of these domains is a few tens of nanometers across and a few hundred nanometers long. The domains display strong preferred orientations involving areas a few hundred nanometers to a few micrometers across.

This report, sponsored the Army's Energy Engineering Analysis Program, provides the Operations and Maintenance (O&M) Energy manager and practitioner with useful information about the top O&M opportunities consistently found across the DoD/Army sector. The target is to help the DoD/Army sector develop a well-structured and organized O&M program.

The alpha emitter plutonium-238 ({sup 238}Pu), which is produced in uranium-fueled, light-water reactors, is used as a thermoelectric power source for space applications. Inhalation of a mixed oxide form of Pu is the most likely mode of exposure of workers and the general public. Occupational exposures to {sup 238}PuO{sub 2} have occurred in association with the fabrication of radioisotope thermoelectric generators. Organs and tissue at risk for deterministic and stochastic effects of {sup 238}Pu-alpha irradiation include the lung, liver, skeleton, and lymphatic tissue. Little has been reported about the effects of inhaled {sup 238}PuO{sub 2} on peripheral blood cell counts in humans. The purpose of this study was to investigate hematological responses after a single inhalation exposure of Beagle dogs to alpha-emitting {sup 238}PuO{sub 2} particles and to extrapolate results to humans.

A concentric thin-shell encircling a Reissner-Nordstr\\"om (RN) black hole screens the internal charge completely to match with an external Schwarzschild (S) black hole. The negative mass thin-shell is shown to be stable against radial perturbations. It is shown further that by reversing the roles of inside (RN) and outside (S) geometries the mass of the appropriate shell becomes positive.

We present an efficient and highly accurate GP-GPU implementation of our community code, PuReMD, for reactive molecular dynamics simulations using the ReaxFF force field. PuReMD and its incorporation into LAMMPS (Reax/C) is used by a large number of research groups worldwide for simulating diverse systems ranging from biomembranes to explosives (RDX) at atomistic level of detail. The sub-femtosecond time-steps associated with ReaxFF strongly motivate significant improvements to per-timestep simulation time through effective use of GPUs. This paper presents, in detail, the design and implementation of PuReMD-GPU, which enables ReaxFF simulations on GPUs, as well as various performance optimization techniques we developed to obtain high performance on state-of-the-art hardware. Comprehensive experiments on model systems (bulk water and amorphous silica) are presented to quantify the performance improvements achieved by PuReMD-GPU and to verify its accuracy. In particular, our experiments show up to 16× improvement in runtime compared to our highly optimized CPU-only single-core ReaxFF implementation. PuReMD-GPU is a unique production code, and is currently available on request from the authors.

In most chiller and boiler central plants, the energy management and control systems (EMCS) monitor and record key operation parameters and energy production continuously. A method was developed to identify potential O&M savings by using the EMCS...

This report was prepared to document the physical, chemical and radiological properties of plutonium oxide materials that were processed in the Plutonium Fuel Form Facility (PuFF) in building 235-F at the Savannah River Plant (now known as the Savannah River Site) in the late 1970s and early 1980s. An understanding of these properties is needed to support current project planning for the safe and effective decontamination and deactivation (D&D) of PuFF. The PuFF mission was production of heat sources to power Radioisotope Thermoelectric Generators (RTGs) used in space craft. The specification for the PuO{sub 2} used to fabricate the heat sources required that the isotopic content of the plutonium be 83 {+-} 1% Pu-238 due to its high decay heat of 0.57 W/g. The high specific activity of Pu-238 (17.1 Ci/g) due to alpha decay makes this material very difficult to manage. The production process produced micron-sized particles which proved difficult to contain during operations, creating personnel contamination concerns and resulting in the expenditure of significant resources to decontaminate spaces after loss of material containment. This report examines high {sup 238}Pu-content material properties relevant to the D&D of PuFF. These relevant properties are those that contribute to the mobility of the material. Physical properties which produce or maintain small particle size work to increase particle mobility. Early workers with {sup 238}PuO{sub 2} felt that, unlike most small particles, Pu-238 oxide particles would not naturally agglomerate to form larger, less mobile particles. It was thought that the heat generated by the particles would prevent water molecules from binding to the particle surface. Particles covered with bound water tend to agglomerate more easily. However, it is now understood that the self-heating effect is not sufficient to prevent adsorption of water on particle surfaces and thus would not prevent agglomeration of particles. Operational experience at PuFF indicates that the Pu-238 contamination was observed to move along surfaces and through High Efficiency Particulate Air (HEPA) filters over time. Recent research into the phenomenon known as alpha recoil offers a potential explanation for this observed behavior. Momentum is conserved when an alpha particle is ejected from a Pu-238 atom due to radioactive decay. Consequently, the entire particle of which that Pu-238 atom is a constituent experiences a movement similar to the recoil of a gun when a bullet is ejected. Furthermore, the particle often fractures in response to Pu-238 atom disintegration (yielding an alpha particle), with a small particle fragment also being ejected in order to conserve momentum. This process results in the continuous size reduction and transport of particles containing Pu-238 atoms, thus explaining movement of contamination along surfaces and through HEPA filters. A better understanding of the thermal behavior of {sup 238}PuO{sub 2} particles is needed to inform the planning process for the PuFF D&D project at the 235-F facility. There has been a concern that the surface temperature of individual particles may be high enough to cause problems with decontamination equipment and materials as a result of heat generation due to radioactive decay. A calculation under conservative assumptions shows that the surface temperature of particles less than about 100 {micro}m diameter is not appreciably above ambient. Since most particles in PuFF are on order of 1 {micro}m in diameter, the effect of particle surface temperature on decontamination equipment and materials is expected to be minimal. The result of this calculation also indicates that thermal imaging, which has been under consideration as a method to monitor the progress of system decontamination efforts would not likely be effective. The use of strippable coating was suggested as a possible alternative to other decontamination techniques. One particular system (i.e., Decon Gel 1101) may offer significant advantages over conventional liquid decontamination solut

A non-destructive, gamma-spectrometric method for verifying the plutonium content of Pu-Be neutron sources has been developed. It is also shown that the isotopic composition and the age of plutonium (Pu) can be determined in the intensive neutron field of these sources by the ``Multi-Group Analysis'' method. Gamma spectra were taken in the far-field of the sample, which was assumed to be cylindrical. The isotopic composition and the age of Pu were determined using a commercial implementation of the Multi-Group Analysis algorithm. The Pu content of the sources was evaluated from the count rates of the gamma-peaks of 239Pu, relying on the assumption that the gamma-rays are coming to the detector parallel to each other. The determination of the specific neutron yields and the problem of neutron damage to the detector are also discussed.

A non-destructive, gamma-spectrometric method for verifying the plutonium content of Pu-Be neutron sources has been developed. It is also shown that the isotopic composition and the age of plutonium (Pu) can be determined in the intensive neutron field of these sources by the ``Multi-Group Analysis'' method. Gamma spectra were taken in the far-field of the sample, which was assumed to be cylindrical. The isotopic composition and the age of Pu were determined using a commercial implementation of the Multi-Group Analysis algorithm. The Pu content of the sources was evaluated from the count rates of the gamma-peaks of 239Pu, relying on the assumption that the gamma-rays are coming to the detector parallel to each other. The determination of the specific neutron yields and the problem of neutron damage to the detector are also discussed.

This is a report on conceptual designs for a long term, 250 years, storage container for plutonium oxide ([sup 238]PuO[sub 2]). These conceptual designs are based on the use of a quartz filter to release the helium generated during the plutonium decay. In this report a review of filter material selection, design concepts, thermal modeling, and filter performance are discussed.

Enthalpy and entropy are thermodynamic quantities critical to determining how and at what temperature a phase transition occurs. At a phase transition, the enthalpy and temperature-weighted entropy differences between two phases are equal (?H=T?S), but there are materials where this balance has not been experimentally or theoretically realized, leading to the idea of hidden order and disorder. In a Pu-1.9 at. % Ga alloy, the ? phase is retained as a metastable state at room temperature, but at low temperatures, the ? phase yields to a mixed-phase microstructure of ?- and ?'-Pu. The previously measured sources of entropy associated withmore »the ?'?? transformation fail to sum to the entropy predicted theoretically. We report an experimental measurement of the entropy of the ?'?? transformation that corroborates the theoretical prediction, and implies that only about 65% of the entropy stabilizing the ? phase is accounted for, leaving a missing entropy of about 0.5 kB/atom. Some previously proposed mechanisms for generating entropy are discussed, but none seem capable of providing the necessary disorder to stabilize the ? phase. This hidden disorder represents multiple accessible states per atom within the ? phase of Pu that may not be included in our current understanding of the properties and phase stability of ?-Pu.« less

1 | IN FORMATION PU BLIC ATION SC H EME TITLE Agency plan for The Australian National University on its website. It will be directly accessible from the webpage foi.anu.edu.au and be identified possible, provide online content that can be searched by web browsers Provide a search function

A neutron howitzer was used to produce 239Np from the targets of natural U and a hot rock. An intrinsic Germanium detector enabled the observations of the gamma rays in the decay of 239Np and a determination of its half life of 2.3 days. This shows that 239Pu had been produced in both targets

When the burn-up is high, the {sup 242}Pu isotopic content becomes more important. The traditional correlation method will fail. The {sup 242}Pu isotopic content in the sample plays an essential role if the neutron coincidence method is used to quantify the total amount of plutonium. In one of the earlier measurements we had a chance to measure an isotopic pure (> 99.95 %) {sup 242}Pu thick sample and realized that the difference in the branching ratio (BR) value among current nuclear data3) for the two important gamma-rays at 103.5-keV and 158.8-keV. In this study, the thick sample was counted on a 15% ORTEC safeguards type HPGe to further improve BR determination of the 159-keV gamma-ray. Furthermore, we have made a thin {sup 242}Pu sample from the thick sample and performed alpha-gamma coincidence measurements. Our preliminary gamma-ray BR results are 4.37(6) E-4, 2.79(8) E-5, and 2.25(8) E-6 for 44.9-keV, 103.5-keV, and 158.9-keV, respectively.

This invention is comprised of a process for converting PuO{sub 2} and U0{sub 2} present in an electrorefiner to the chlorides, by contacting the PuO{sub 2} and U0{sub 2} with Li metal in the presence of an alkali metal chloride salt substantially free of rare earth and actinide chlorides for a time and at a temperature sufficient to convert the U0{sub 2} and PuO{sub 2} to metals while converting Li metal to Li{sub 2}O. Li{sub 2}O is removed either by reducing with rare earth metals or by providing an oxygen electrode for transporting 0{sub 2} out of the electrorefiner and a cathode, and thereafter applying an emf to the electrorefiner electrodes sufficient to cause the Li{sub 2}O to disassociate to 0{sub 2} and Li metal but insufficient to decompose the alkali metal chloride salt. The U and Pu and excess lithium are then converted to chlorides by reaction with CdCl{sub 2}.

A process is described for converting PuO[sub 2] and UO[sub 2] present in an electrorefiner to the chlorides, by contacting the PuO[sub 2] and UO[sub 2] with Li metal in the presence of an alkali metal chloride salt substantially free of rare earth and actinide chlorides for a time and at a temperature sufficient to convert the UO[sub 2] and PuO[sub 2] to metals while converting Li metal to Li[sub 2]O. Li[sub 2]O is removed either by reducing with rare earth metals or by providing an oxygen electrode for transporting O[sub 2] out of the electrorefiner and a cathode, and thereafter applying an emf to the electrorefiner electrodes sufficient to cause the Li[sub 2]O to disassociate to O[sub 2] and Li metal but insufficient to decompose the alkali metal chloride salt. The U and Pu and excess lithium are then converted to chlorides by reaction with CdCl[sub 2].

A process for converting PuO.sub.2 and UO.sub.2 present in an electrorefiner to the chlorides, by contacting the PuO.sub.2 and UO.sub.2 with Li metal in the presence of an alkali metal chloride salt substantially free of rare earth and actinide chlorides for a time and at a temperature sufficient to convert the UO.sub.2 and PuO.sub.2 to metals while converting Li metal to Li.sub.2 O. Li.sub.2 O is removed either by reducing with rare earth metals or by providing an oxygen electrode for transporting O.sub.2 out of the electrorefiner and a cathode, and thereafter applying an emf to the electrorefiner electrodes sufficient to cause the Li.sub.2 O to disassociate to O.sub.2 and Li metal but insufficient to decompose the alkali metal chloride salt. The U and Pu and excess lithium are then converted to chlorides by reaction with CdCl.sub.2.

Enthalpy and entropy are thermodynamic quantities critical to determining how and at what temperature a phase transition occurs. At a phase transition, the enthalpy and temperature-weighted entropy differences between two phases are equal (?H=T?S), but there are materials where this balance has not been experimentally or theoretically realized, leading to the idea of hidden order and disorder. In a Pu-1.9 at. % Ga alloy, the ? phase is retained as a metastable state at room temperature, but at low temperatures, the ? phase yields to a mixed-phase microstructure of ?- and ?'-Pu. The previously measured sources of entropy associated with the ?'?? transformation fail to sum to the entropy predicted theoretically. We report an experimental measurement of the entropy of the ?'?? transformation that corroborates the theoretical prediction, and implies that only about 65% of the entropy stabilizing the ? phase is accounted for, leaving a missing entropy of about 0.5 kB/atom. Some previously proposed mechanisms for generating entropy are discussed, but none seem capable of providing the necessary disorder to stabilize the ? phase. This hidden disorder represents multiple accessible states per atom within the ? phase of Pu that may not be included in our current understanding of the properties and phase stability of ?-Pu.

This report provides guideline estimates for Pu-239 mass loadings in selected burial ground culverts. The relatively high recorded Pu-239 contents of these culverts have been appraised as suspect relative to criticality concerns, because they were assayed only with the solid waste monitor (SWM) per gamma-ray counting. After 1985, subsequent waste was also assayed with the neutron coincidence counter (NCC), and a comparison of the assay methods showed that the NCC generally yielded higher assays than the SWM. These higher NCC readings signaled a need to conduct non-destructive/non-intrusive nuclear interrogations of these culverts, and a technical team conducted scoping measurements to illustrate potential assay methods based on neutron and/or gamma counting. A fast/slow neutron method has been developed to estimate the Pu-239 in the culverts. In addition, loading records include the SWM assays of all Pu-239 cuts of some of the culvert drums and these data are useful in estimating the corresponding NCC drum assays from NCC vs SWM data. Together, these methods yield predictions based on direct measurements and statistical inference.

Progress in the Savannah River /sup 238/Pu Fuel Form Program is summarized. Work during this period concentrated on the extensive cracking of the /sup 238/PuO/sub 2/ fuel form prior to encapsulation in the iridium containment shell for heat sources. This cracking results in increased recycle cost and decreased production efficiency. To better understand this cracking, Savannah River Laboratory (SRL) has made an extensive review of the development of /sup 238/PuO/sub 2/ fuel forms from small-scale Multi-hundred Watt (MHW) pellets through the current GPHS full-scale pellet production. Historically, /sup 238/PuO/sub 2/ fuel has almost always been uncracked after hot pressing in a graphite die, but has emerged cracked and fragile from the final heat-treatment furnace. The cracking tendency depends on the microstructure of the fuel form and on the hot pressing conditions used to fabricate it. In general, a microstructure of large intershard porosity is more desirable because it allows internal gas to escape more readily and it can absorb more reoxidation strain. Studies of the GPHS microstructure showed that the internal structures of typical GPHS Pellets fabricated at LANL and in the PEF differed significantly. The LANL pellets had severe density gradients and were extensively cracked.

The solubility of different forms of precipitated 242PuO2(am) were examined in solutions containing aqueous Fe(II) over a range of pH values. The first series of 242PuO2(am) suspensions were prepared from a 242Pu(IV) stock that had been treated with thenoyltrifluoroacetone (TTA) to remove the 241Am originating from the decay of 241Pu. These 242PuO2(am) suspensions showed much higher solubilities at the same pH value and Fe(II) concentration than previous studies using 239PuO2(am). X ray absorption fine structure (XAFS) spectroscopy of the precipitates showed a substantially reduced Pu-Pu backscatter over that previously observed in 242PuO2(am) precipitates, indicating that the 242PuO2(am) precipitates purified using TTA lacked the long range order previously found in 239PuO2(am) precipitates. The Pu(IV) stock solution was subsequently repurified using an ion exchange resin and an additional series of 242PuO2(am) precipitates prepared. These suspensions showed higher redox potentials and total aqueous Pu concentrations than the TTA purified stock solution. The higher redox potential and aqueous Pu concentrations were in general agreement with previous studies on 242PuO2(am) precipitates, presumably due to the removal of possible organic compounds originally present in the TTA purified stock. 242PuO2(am) suspensions prepared with both stock solutions showed almost identical solubilities in Fe(II) containing solutions even though the initial aqueous Pu concentrations before the addition of Fe(II) were orders of magnitude different. By examining the solubility of 242PuO2(am) prepared from both stocks in this way we have essentially approached equilibrium from both the undersaturated and oversaturated conditions. The final aqueous Pu concentrations are predictable using a chemical equilibrium model which includes the formation of a nanometer sized Fe(III) reaction product, identified in the 242PuO2(am) suspension both by use of 57Fe Mössbauer spectroscopy and transmission electron microscopy (TEM) analysis.

the O&M energy savings potential in each of the 104 schools. The analysis is based on a year of data monitored at Sims and Dunbar Schools, along with site visits and short-term measurements of hourly consumption to determine the baseload electricity..., their occupancy rates and the O&M savings potential. Table 2 provides detailed information of potential electricity savings in each of the 104 schools. We note that about half of the savings would result from careful nighttime shut-down on weekdays, State Energy...

Passive neutron coincidence counting is capable of 1% assay accuracy for pure, well-characterized PuO/sub 2/ samples that contain plutonium masses from a few tens of grams to several kilograms. Moisture in the sample can significantly bias the assay high by changing the (..cap alpha..,n) neutron production, the sample multiplication, and the detection efficiency. Monte Carlo calculations and an analytical model of coincidence counting have been used to quantify the individual and cumulative effects of moisture biases for two PuO/sub 2/ sample sizes and a range of moisture levels from 0 to 9 wt %. Results of the calculations suggest a simple correction procedure for moisture bias that is effective from 0 to 3 wt % H/sub 2/O. The procedure requires that the moisture level in the sample be known before the coincidence measurement.

We have designed and successfully employed a novel microbeam on large grain sample concept to conduct high resolution inelastic x-ray scattering (HRIXS) experiments to map the full phonon dispersion curves of an fcc {delta}-phase Pu-Ga alloy. This approach obviates experimental difficulties with conventional inelastic neutron scattering due to the high absorption cross section of the common {sup 239}Pu isotope and the non-availability of large (mm size) single crystal materials for Pu and its alloys. A classical Born von-Karman force constant model was used to model the experimental results, and no less than 4th nearest neighbor interactions had to be included to account for the observation. Several unusual features including, a large elastic anisotropy, a small shear elastic modulus, (C{sub 11}-C{sub 12})/2, a Kohn-like anomaly in the T{sub 1}[011] branch, and a pronounced softening of the T[111] branch towards the L point in the Brillouin are found. These features may be related to the phase transitions of plutonium and to strong coupling between the crystal structure and the 5f valence instabilities. Our results represent the first full phonon dispersions ever obtained for any Pu-bearing material, thus ending a 40-year quest for this fundamental data. The phonon data also provide a critical test for theoretical treatments of highly correlated 5f electron systems as exemplified by recent dynamical mean field theory (DMFT) calculations for {delta}-plutonium. We also conducted thermal diffuse scattering experiments to study the T(111) dispersion at low temperatures with an attempt to gain insight into bending of the T(111) branch in relationship to the {delta} {yields} {alpha}{prime} transformation.

Between 1944 and 1989, the Hanford Site produced 60 percent (54.5 metric tons) of the United States weapons plutonium and produced an additional 12.9 metric tons of fuels-grade plutonium. High activity wastes, including plutonium lost from the separations processes used to isolate the plutonium, were discharged to underground storage tanks during these operations. Plutonium in the Hanford tank farms is estimated to be {approx}700 kg but may be up to {approx}1000 kg. Despite these apparent large quantities, the average plutonium concentration in the {approx}200 million liter tank waste volume is only about 0.003 grams per liter ({approx}0.0002 wt%). The plutonium is largely associated with low solubility metal hydroxide/oxide sludges where its low concentration and intimate mixture with neutron-absorbing elements (e.g., iron) are credited in nuclear criticality safety. However, concerns have been expressed that plutonium, in the form of plutonium hydrous oxide, PuO{sub 2} {center_dot} xH{sub 2}O, could undergo sufficient crystal growth through Ostwald ripening in the alkaline tank waste to potentially be separable from neutron absorbing constituents by settling or sedimentation. It was found that plutonium that entered the alkaline tank waste by precipitation through neutralization from acid solution is initially present as 2- to 3-nm (0.002- to 0.003-{mu}m) scale PuO{sub 2} {center_dot} xH{sub 2}O crystallite particles and grows from that point at exceedingly slow rates, posing no risk to physical segregation. These conclusions are reached by both general considerations of Ostwald ripening and specific observations of the behaviors of PuO{sub 2} and PuO{sub 2} {center_dot} xH{sub 2}O upon aging in alkaline solution.

Transcriptional dysregulation is associated with haematological malignancy. Although mutations of the key haematopoietic transcription factor PU.1 are rare in human acute myeloid leukemia (AML), they are common in murine models of radiation...

The concept for the system described herein is an active/passive Nuclear Materials Identification System{sup 2} (NMIS) that incorporates gamma ray spectrometry{sup 3}. This incorporation of gamma ray spectrometry would add existing capability into this system. This Multiple Attribute System can determine a wide variety of attributes for Pu and highly enriched uranium (HEU) of which a selected subset could be chosen. This system can be built using commercial off the shelf (COTS) components. NMIS systems are at All-Russian Scientific Research Institute of Experimental Physics (VNIIEF) and Russian Federal Nuclear Center Institute of Technical Physics, (VNIITF) and measurements with Pu have been performed at VNIIEF and analyzed successfully for mass and thickness of Pu. NMIS systems are being used successfully for HEU at the Y-12 National Security Complex. The use of active gamma ray spectrometry for high explosive HE and chemical agent detection is a well known activation analysis technique, and it is incorporated here. This report describes the system, explains the attribute determination methods for fissile materials, discusses technical issues to be resolved, discusses additional development needs, presents a schedule for building from COTS components, and assembly with existing components, and discusses implementation issues such as lack of need for facility modification and low radiation exposure.

This paper present the results of a series of calculations made to determine the {sup 238}Pu production potential of several advanced target assembly designs in the Fast Flux Test Facility (FFTF). These calculations show that by using advanced target designs the intimately mix the {sup 237}Np target material with an yttrium hydride moderator, the FFTF has the potential of producing up to 30 kg of high-quality {sup 238}Pu per year.

Plutonium-239 is now being processed in HB-Line and H-Canyon as well as FB-Line and F-Canyon. As part of the effort to upgrade the Authorization Basis for H Area facilities relative to nuclear criticality, a literature review of Pu polymer characteristics was conducted to establish a more quantitative vs. qualitative technical basis for safe operations. The results are also applicable to processing in F Area facilities.The chemistry of Pu polymer formation, precipitation, and depolymerization is complex. Establishing limits on acid concentrations of solutions or changing the valence to Pu(III) or Pu(VI) can prevent plutonium polymer formation in tanks in the B lines and canyons. For Pu(IV) solutions of 7 g/L or less, 0.22 M HNO3 prevents polymer formation at ambient temperature. This concentration should remain the minimum acid limit for the canyons and B lines when processing Pu-239 solutions. If the minimum acid concentration is compromised, the solution may need to be sampled and tested for the presence of polymer. If polymer is not detected, processing may proceed. If polymer is detected, adding HNO3 to a final concentration above 4 M is the safest method for handling the solution. The solution could also be heated to speed up the depolymerization process. Heating with > 4 M HNO3 will depolymerize the solution for further processing.Adsorption of Pu(IV) polymer onto the steel walls of canyon and B line tanks is likely to be 11 mg/cm2, a literature value for unpolished steel. This value will be confirmed by experimental work. Tank-to-tank transfers via steam jets are not expected to produce Pu(IV) polymer unless a larger than normal dilution occurs (e.g., >3 percent) at acidities below 0.4 M.

Excited states in the {sup 240}Pu nucleus have been studied by means of the (p,t) reaction using the Q3D spectrometer and the focal plane detector from Munich. The comparison between experimental angular distributions and the DWBA calculations allowed the extraction of relative two-neutron transfer strengths. These observables may reveal important information about the structure of different states. The experimental two neutron strength for the 0{sup +}{sub 2} and 0{sup +}{sub 3} states is found in good agreement with the predictions of the IBA model, confirming the double octupole nature for the 0{sup +}{sub 2} state proposed in the previous studies.

The Department of Energy (DOE) has contracted with Asea Brown Boveri-Combustion Engineering (ABB-CE) to provide information on the capability of ABB-CE`s System 80 + Advanced Light Water Reactor (ALWR) to transform, through reactor burnup, 100 metric tonnes (MT) of weapons grade plutonium (Pu) into a form which is not readily useable in weapons. This information is being developed as part of DOE`s Plutonium Disposition Study, initiated by DOE in response to Congressional action. This document Volume 2, provides a discussion of: Plutonium Fuel Cycle; Technology Needs; Regulatory Considerations; Cost and Schedule Estimates; and Deployment Strategy.

A method of analysis of fluctuation in the delayed neutron yield on the basis of the multimodal fission model was applied to the low-energy resolved resonances for Pu-239. The present calculation using recent data of the fluctuation of the mode branching ratios for the resolved resonances showed both positive and negative resonance structure in the delayed neutron yield relative to the thermal neutron value. This is in contrast to the U-235 case, for which mainly negative dips of about -3.5% were predicted.

A new rapid method for the determination of {sup 237}Np and Pu isotopes in soil and sediment samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used for large soil samples. The new soil method utilizes an acid leaching method, iron/titanium hydroxide precipitation, a lanthanum fluoride soil matrix removal step, and a rapid column separation process with TEVA Resin. The large soil matrix is removed easily and rapidly using this two simple precipitations with high chemical recoveries and effective removal of interferences. Vacuum box technology and rapid flow rates are used to reduce analytical time.

An experiment aimed at the synthesis of isotopes of element 120 has been performed using the {sup 244}Pu({sup 58}Fe,xn){sup 302-x} 120 reaction. No decay chains consistent with fusion-evaporation reaction products were observed during an irradiation with a beam dose of 7.1 x 10{sup 18} 330-MeV {sup 58}Fe projectiles. The sensitivity of the experiment corresponds to a cross section of 0.4 pb for the detection of one decay.

A method for extracting and reclaiming metals from scrap CdTe photovoltaic cells and manufacturing waste by leaching the waste with a leaching solution comprising nitric acid and water, skimming any plastic material from the top of the leaching solution, separating the glass substrate from the liquid leachate and electrolyzing the leachate to separate Cd from Te, wherein the Te is deposits onto a cathode while the Cd remains in solution.

This work establishes the criticality safety technical basis to increase the fissile mass limit from 120 grams to 200 grams for Type A 55-gallon drums and their equivalents. Current RHWM fissile mass limit is 120 grams Pu for Type A 55-gallon containers and their equivalent. In order to increase the Type A 55-gallon drum limit to 200 grams, a few additional criticality safety control requirements are needed on moderators, reflectors, and array controls to ensure that the 200-gram Pu drums remain criticality safe with inadvertent criticality remains incredible. The purpose of this work is to analyze the use of 200-gram Pu drum mass limit for waste storage operations in Radioactive and Hazardous Waste Management (RHWM) Facilities. In this evaluation, the criticality safety controls associated with the 200-gram Pu drums are established for the RHWM waste storage operations. With the implementation of these criticality safety controls, the 200-gram Pu waste drum storage operations are demonstrated to be criticality safe and meet the double-contingency-principle requirement per DOE O 420.1.

A combined Nuclear Materials Identification System (NMIS)-gamma ray spectrometry system can be used passively to obtain the following attributes of Pu: presence, fissile mass, 240/239 ratio, and metal vs. oxide. This system can also be used with a small, portable, DT neutron generator to measure the attributes of highly enriched uranium (HEU): presence, fissile mass, enrichment, metal vs. oxide; and detect the presence of high explosives (HE). For the passive system, time-dependent coincidence distributions can be used for the presence, fissile mass, metal vs. oxide for Pu, and gamma-ray spectrometry can be used for 239/240 ratio and presence. So presence can be confirmed by two methods. For the active system with a DT neutron generator, all four attributes for both Pu and HEU can be determined from various features of the time-dependent coincidence distribution measurements for both Pu and HEU. Active gamma ray spectrometry would also give presence and 240/239 ratio for Pu, enrichment for HEU, and metal vs. oxide for both. Active gamma ray spectrometry would determine the presence of HE. The various features of time-dependent coincidence distributions and gamma ray spectrometry that determine these attributes are discussed with some examples from previous determinations.

The electrochemical behavior of ZnTe and CdTe compound semiconductors dissolved in molten ZnCl[subscript 2] and equimolar CdCl[subscript 2]–KCl, respectively, was examined. In these melts dissolved Te is present as the ...

GRPAUT is a modular program for performing automated Pu isotopic analysis supplied to the International Atomic Energy Agency (IAEA) per ISPO Task A.76. Section I of this user's guide for GRPAUT presents an overview of the various programs and disk files that are used in performing a Pu isotopic analysis. Section II describes the program GRFEDT which is used in creating and editing the analysis parameter file that contains all the spectroscopic information needed at runtime by GRPAUT. An example of the dialog and output of GRFEDT is shown in Appendix B. Section III describes the operation of the various GRPAUT modules: GRPNL2, the peak stripping module; EFFCH2, the efficiency calculation module; and ISOAUT, the isotopic calculation module. (A description of the peak fitting methodology employed by GRPNL2 is presented in Appendix A.) Finally, Section IV outlines the procedure for determining the peak shape constants for a detector system and describes the operation of the program used to create and edit the peak shape parameter files. An output of GRPAUT, showing an example of a complete isotopic analysis, is presented in Appendix C. Source listings of all the Fortran programs supplied to the Agency under ISPO Task A.76 are contained in Appendix E.

The compatibility of Mo-50 wt % Re with /sup 238/PuO/sub 2/ was investigated after heat treatments of up to 720 days at 800/sup 0/C and 180 days at 1000/sup 0/C. At 800/sup 0/C, a 1-..mu..m thick, continuous layer of molybdenum oxide resulted. At 1000/sup 0/C, the oxide reaction product contained some plutonium and did not appear continuous. At 1000/sup 0/C, a layer of intermetallic formed at the Mo-Re edge, beneath the oxide layer, creating a barrier between the Mo-50 wt % Re and the /sup 238/PuO/sub 2/. The intermetallic layer was promoted by the iron impurity in the /sup 238/PuO/sub 2/.

The nuclear fuel cycle generates a considerable amount of radioactive waste, which often includes nuclear fission products, such as strontium-90 ({sup 90}Sr) and cesium-137 ({sup 137}Cs), and actinides such as uranium (U) and plutonium (Pu). When released into the environment, large quantities of these radionuclides can present considerable problems to man and biota due to their radioactive nature and, in some cases as with the actinides, their chemical toxicity. Radionuclides are expected to decay at a known rate. Yet, research has shown the rate of elimination from an ecosystem to differ from the decay rate due to physical, chemical and biological processes that remove the contaminant or reduce its biological availability. Knowledge regarding the rate by which a contaminant is eliminated from an ecosystem (ecological half-life) is important for evaluating the duration and potential severity of risk. To better understand a contaminants impact on an environment, consideration should be given to plants. As primary producers, they represent an important mode of contamination transfer from sediments and soils into the food chain. Contaminants that are chemically and/or physically sequestered in a media are less likely to be bio-available to plants and therefore an ecosystem.

The main source of artificial radioactivity in the world`s oceans can be attributed to worldwide fallout from atmospheric nuclear weapons testing. Measurements of selected artificial radionuclides in the Pacific Ocean were first conducted in the 1960`s where it was observed that fallout radioactivity had penetrated the deep ocean. Extensive studies carried out during the 1973-74 GEOSECS provided the first comprehensive data on the lateral and vertical distributions of {sup 9O}Sr, {sup 137}Cs and Pu isotopes in the Pacific on a basin wide scale. Estimates of radionuclide inventories in excess of amounts predicted to be delivered by global fallout alone were attributed to close-in fallout and tropospheric inputs from early U.S. tests conducted on Bikini and Enewetak Atolls in the Equatorial Pacific. In general, levels of fallout radionuclides (including {sup 9O}Sr, {sup 137}Cs and Pu isotopes) in the surface waters of the Pacific Ocean have decreased considerably over the past 4 decades and are now much more homogeneously distributed. Resuspension and the subsequent deposition of fallout radionuclides from previously deposited debris on land has become an important source term for the surface ocean. This can be clearly seen in measurements of fallout radionuclides in mineral aerosols over the Korean Peninsula (Yellow dust events). Radionuclides may also be transported from land to sea in river runoff-these transport mechanisms are more important in the Pacific Ocean where large quantities of river water and suspended sands/fluvial sediments reach the coastal zone. Another unique source of artificial radionuclides in the Pacific Ocean is derived from the slow resolubilization and transport of radionuclides deposited in contaminated lagoon and slope sediments near U.S. and French test sites. Although there is a small but significant flux of artificial radionuclides depositing on the sea floor, > 80% of the total 239, {sup 240}Pu inventory and > 95% of the total {sup 137}Cs inventory remains in the water column. Studies conducted through the 1980`s appear to be consistent with earlier findings and indicate that radionuclide inventories in mid-northern latitudes are at least a factor of two above those expected from global fallout alone. The long term persistence of close-in and/or stratospheric fallout from nuclear weapons testing in the Marshall Islands still appears to be the only plausible explanation for this anomaly.

A Pu-2 at.% Ga alloy specimen is slowly compressed to {approx}1 GPa in a large volume moissanite anvil cell to induce the face-centered cubic {delta} to simple monoclinic {alpha}{prime} phase transformation. Optical microscopy, x-ray diffraction, and transmission electron microscopy of the specimen recovered to ambient pressure reveal that the vast majority of the microstructure consists of the {alpha}{prime} phase with grain sizes ranging from 10 nm to several hundred nm, with the remainder being {delta} phase dispersed between the {alpha}{prime} grains. This morphology is in contrast to the transformation product of the low-temperature isothermal martensite in which the lath-shaped {alpha}{prime} particles are {approx}20 {micro}m by 2 {micro}m.

For the past half century, the National Aeronautics and Space Administration (NASA) has used Radioisotope Thermoelectric Generators (RTG) to power deep space satellites. Fabricating heat sources for RTGs, specifically General Purpose Heat Sources (GPHSs), has remained essentially unchanged since their development in the 1970s. Meanwhile, 30 years of technological advancements have been made in the applicable fields of chemistry, manufacturing and control systems. This paper evaluates alternative processes that could be used to produce Pu 238 fueled heat sources. Specifically, this paper discusses the production of the plutonium-oxide granules, which are the input stream to the ceramic pressing and sintering processes. Alternate chemical processes are compared to current methods to determine if alternative fabrication processes could reduce the hazards, especially the production of respirable fines, while producing an equivalent GPHS product.

Hartree-Fock-Bogoliubov calculations of hot fission in {sup 240}Pu have been performed with a newly-implemented code that uses the D1S finite-range effective interaction. The hot-scission line is identified in the quadrupole-octupole-moment coordinate space. Fission-fragment shapes are extracted from the calculations. A benchmark calculation for {sup 226}Th is obtained and compared to results in the literature. In addition, technical aspects of the use of HFB calculations for fission studies are examined in detail. In particular, the identification of scission configurations, the sensitivity of near-scission calculations to the choice of collective coordinates in the HFB iterations, and the formalism for the adjustment of collective-variable constraints are discussed. The power of the constraint-adjustment algorithm is illustrated with calculations near the critical scission configurations with up to seven simultaneous constraints.

The Department of Energy (DOE) has contracted with Asea Brown Boveri-Combustion Engineering (ABB-CE) to provide information on the capability of ABB-CE`s System 80 + Advanced Light Water Reactor (ALWR) to transform, through reactor burnup, 100 metric tonnes (MT) of weapons grade plutonium (Pu) into a form which is not readily useable in weapons. This information is being developed as part of DOE`s Plutonium Disposition Study, initiated by DOE in response to Congressional action. This document, Volume 1, presents a technical description of the various elements of the System 80 + Standard Plant Design upon which the Plutonium Disposition Study was based. The System 80 + Standard Design is fully developed and directly suited to meeting the mission objectives for plutonium disposal. The bass U0{sub 2} plant design is discussed here.

Using a broad range of gamma-ray uranium standards and two plutonium samples of known isotopic content, list mode gamma ray information from two Compton suppressed and one planar HPGe detectors were analyzed according to the time information of the signals. Interferences from Cs-137 were introduced. In this study, we extended singles measurements by exploring the potential of simultaneously using both singles and coincidence data for U/Pu assay. The main goals of this exploratory study are: 1) whether one will be able to use coincidence information in addition to the complicated 100-keV unfolding to obtain extra information of uranium and plutonium isotopic ratios, and 2) with higher energy interference gamma-rays from isotopes such as Cs-137, can the coincidence information help to provide the isotopic information. (authors)

The energy dependence of the relative yield of delayed neutrons in an 8-group model representation was obtained for monoenergetic neutron induced fission of sup 2 sup 3 sup 9 Pu. A comparison of this data with the available experimental data by other was made in terms of the mean half-life of the delayed neutron precursors.

To address SNJV concerns that fluoride in Nevada Test site (NTS) groundwaters may impact radionuclide speciation and transport, NTS water quality databases were obtained and scanned for analyses with high fluoride concentrations (> 10 mg/L). The aqueous speciation of nine representative samples of these groundwaters with added trace amounts of uranium (U), neptunium (Np), plutonium (Pu), americium (Am) and europium (Eu) was then calculated with the computer code EQ3NR assuming a temperature of 25 C, using currently available thermodynamic data for these species. Under conditions where U(VI), Np(V), Pu(IV), Am(III) and Eu(III) dominate, F complexes are insignificant (<1 mole %) for U, Np, Pu and Am. Eu-F complexes may be significant in groundwaters that lack bicarbonate, possess pH values less than about 7 at ambient temperatures, or contain F in extremely high concentrations (e.g. > 50 mg/L). The objective is to evaluate the extent to which fluoride in NTS groundwaters complex U(VI), Np(V), Pu(IV), Am(III) and Eu(III). The approach used is to screen existing databases of groundwater chemistry at NTS for waters with high fluoride concentrations and calculate the extent to which fluoride complexes with the nuclides of interest in these waters.

A method for extracting and reclaiming metals from scrap CdTe photovoltaic cells and manufacturing waste by leaching the metals in dilute nitric acid, leaching the waste with a leaching solution comprising nitric acid and water, skimming any plastic material from the top of the leaching solution, separating the glass substrate from the liquid leachate, adding a calcium containing base to the leachate to precipitate Cd and Te, separating the precipitated Cd and Te from the leachate, and recovering the calcium-containing base. 3 figs.

A method for extracting and reclaiming metals from scrap CdTe photovoltaic cells and manufacturing waste by leaching the metals in dilute nitric acid, leaching the waste with a leaching solution comprising nitric acid and water, skimming any plastic material from the top of the leaching solution, separating the glass substrate from the liquid leachate, adding a calcium containing base to the leachate to precipitate Cd and Te, separating the precipitated Cd and Te from the leachate, and recovering the calcium-containing base.

Residual impurities in manganese (Mn) are a big obstacle to obtaining high-performance CdMnTe (CMT) X-ray and gamma-ray detectors. Generally, the zone-refining method is an effective way to improve the material's purity. In this work, we purified the MnTe compounds combining the zone-refining method with molten Te, which has a very high solubility for most impurities. We confirmed the improved purity of the material by glow-discharge mass spectrometry (GDMS). We also found that CMT crystals from a multiply-refined MnTe source, grown by the vertical Bridgman method, yielded better performing detectors.

Narrow-gap lead telluride crystal is an important thermoelectric and mid-infrared material in which phonon functionality is a critical issue to be explored. In this Letter, efficient phonon blockage by forming a polar CdTe/PbTe heterojunction is explicitly observed by Raman scattering. The unique phonon screening effect can be interpreted by recent discovery of high-density two dimensional electrons at the polar CdTe/PbTe(111) interface which paves a way for design and fabrication of thermoelectric devices.

After the severe core damage of Fukushima Dai-Ichi Nuclear Power Station, radioactive material leaked from the reactor buildings. As part of monitoring of radioactivity in the site, measurements of radioactivity in soils at three fixed points have been performed for {sup 134}Cs and {sup 137}Cs with gamma-ray spectrometry and for Pu, Pu, and {sup 240}Pu with {alpha}-ray spectrometry. Correlations of radioactivity ratios of {sup 134}Cs to {sup 137}Cs, and {sup 238}Pu to the sum of {sup 239}Pu and {sup 240}Pu with fuel burnup were studied by using theoretical burnup calculations and measurements on isotopic inventories, and compared with the Cs and Pu radioactivity rations in the soils. The comparison indicated that the burnup of the fuel sourcing the radioactivity was from 18 to 38 GWd/t, which corresponded to that of the fuel in the highest power and, therefore, the highest decay heat in operating high-burnup fueled BWR cores. (authors)

GaTe semiconductor is used as a room-temperature radiation detector. GaTe has useful properties for radiation detectors: ideal bandgap, favorable mobilities, low melting point (no evaporation), non-hygroscopic nature, and availability of high-purity starting materials. The detector can be used, e.g., for detection of illicit nuclear weapons and radiological dispersed devices at ports of entry, in cities, and off shore and for determination of medical isotopes present in a patient.

Nuclear power is an attractive alternative to hydrocarbon-based energy production at a time when moving away from carbon-producing processes is widely accepted as a significant developmental need. Hence, the radioactive actinide power sources for this industry are necessarily becoming more widespread, which is accompanied by the increased risk of exposure to both biological and environmental systems. This, in turn, requires the development of technology designed to remove such radioactive threats efficiently and selectively from contaminated material, whether that be contained nuclear waste streams or the human body. Raymond and coworkers (University of California, Berkeley) have for decades investigated the interaction of biologically-inspired, hard Lewis-base ligands with high-valent, early-actinide cations. It has been established that such ligands bind strongly to the hard Lewis-acidic early actinides, and many poly-bidentate ligands have been developed and shown to be effective chelators of actinide contaminants in vivo. Work reported herein explores the effect of ligand geometry on the linear U(IV) dioxo dication (uranyl, UO{sub 2}{sup 2+}). The goal is to utilize rational ligand design to develop ligands that exhibit shape selectivity towards linear dioxo cations and provides thermodynamically favorable binding interactions. The uranyl complexes with a series of tetradentate 3-hydroxy-pyridin-2-one (3,2-HOPO) ligands were studied in both the crystalline state as well as in solution. Despite significant geometric differences, the uranyl affinities of these ligands vary only slightly but are better than DTPA, the only FDA-approved chelation therapy for actinide contamination. The terepthalamide (TAM) moiety was combined into tris-beidentate ligands with 1,2- and 3,2-HOPO moieties were combined into hexadentate ligands whose structural preferences and solution thermodynamics were measured with the uranyl cation. In addition to achieving coordinative saturation, these ligands exhibited increased uranyl affinity compared to bis-Me-3,2-HOPO ligands. This result is due in part to their increased denticity, but is primarily the result of the presence of the TAM moiety. In an effort to explore the relatively unexplored coordination chemistry of Pu(IV) with bidentate moieties, a series of Pu(IV) complexes were also crystallized using bidentate hydroxypyridinone and hydroxypyrone ligands. The geometries of these complexes are compared to that of the analogous Ce(IV) complexes. While in some cases these showed the expected structural similarities, some ligand systems led to significant coordination changes. A series of crystal structure analyses with Ce(IV) indicated that these differences are most likely the result of crystallization condition differences and solvent inclusion effects.

ZPPR (Zero Power Physics Reactor) is a research reactor that has been used to investigate breeder reactor fuel designs. The reactor has been dismantled but its fuel is still stored there. Of concern are its plutonium containing metal fuel elements which are enclosed in stainless steel cladding with gas space filled with helium–argon gas and welded air tight. The fuel elements which are 5.08 cm by 0.508 cm up to 20.32 cm long (2 in × 0.2 in × 8 in) were manufactured in 1968. A few of these fuel elements have failed releasing contamination raising concern about the general state of the large number of other fuel elements. Inspection of the large number of fuel elements could lead to contamination release so analytical studies have been conducted to estimate the probability of failed fuel elements. This paper investigates the possible fuel failures due to generation of helium in the metal fuel from the decay of Pu and its possible damage to the fuel cladding from metal fuel expansion or from diffusion of helium into the fuel gas space. This paper (1) calculates the initial gas loading in a fuel element and its internal free volume after it has been brought into the atmosphere at ZPPR, (2) shows that the amount of helium generated by decay of Pu over 46 years since manufacture is significantly greater than this initial loading, (3) determines the amount of fuel swelling if the helium stays fixed in the fuel plate and estimates the amount of helium which diffuses out of the fuel plate into the fuel plenum assuming the helium does not remain fixed in the fuel plate but can diffuse to the plenum and possibly through the cladding. Since the literature is not clear as to which possibility occurs, as with Schroedinger’s cat, both possibilities are analyzed. The paper concludes that (1) if the gas generated is fixed in the fuel, then the fuel swelling it can cause would not cause any fuel failure and (2) if the helium does diffuse out of the fuel (in accordance diffusivities estimated from the literature), then it is unlikely that fuel element bulging will occur.

This report evaluates alternative processes that could be used to produce Pu-238 fueled General Purpose Heat Sources (GPHS) for radioisotope thermoelectric generators (RTG). Fabricating GPHSs with the current process has remained essentially unchanged since its development in the 1970s. Meanwhile, 30 years of technological advancements have been made in the fields of chemistry, manufacturing, ceramics, and control systems. At the Department of Energy’s request, alternate manufacturing methods were compared to current methods to determine if alternative fabrication processes could reduce the hazards, especially the production of respirable fines, while producing an equivalent GPHS product. An expert committee performed the evaluation with input from four national laboratories experienced in Pu-238 handling.

Two new multivariate calibration methods for using all of the relevant spectral information are applied to the determination of plutonium. The analyte response signal originates from the absorbance spectrum of Pu(III)from 500 to 900 nm. Partial least squares (PLS) regression gives an average absolute error of 0.114 /+-/ 0.108 mg when predicting plutonium content of standards containing 65 to 90 mg total plutonium. PLS uses all of the signal in the spectrum and is a more robust calibration procedure than a method based on absorbances at five wavelengths. Another calibration procedure involving least squares curve fitting (LSCF) fits either the entire spectrum or individual spectral intervals derived from standards to spectra of unknowns. In addition, an arbitrary linear base line can be included. The best LSCF option for the same calibration and test set as used for PLS was the full spectrum (522 to 900 nm) with a linear base-line option. The average absolute error when predicting with LSCF was 0.130 /+-/ 0.092 mg plutonium. LSCF has an advantage over PLS in that the linear base line can account for certain types of interferences that have been observed for this plutonium assay procedure. An example is given. 6 refs., 3 figs., 5 tabs.

A nondestructive neutron activation method for determining gadolinium content for reactor construction materials was developed. The method uses a Pu-Be neutron source capable of giving 10/sup 8/ neutrons per second and the neutron reaction with a /sup 160/Gd target. To determine the flux attenuation, induced-activity distributions were measured along the radius with artificial compacts of Al/sub 2/O/sub 3/ + Gd/sub 2/O/sub 3/ specimens with varying gadolinium contents. The specimens were irradiated in unscreened and screened containers. The ratios of the unfiltered and filtered activities were not more than 1.06 +/- 0.04. The dependence of the gamma-ray absorption coefficient on gadolinium content and the effect of gadolinium content on the count rate due to /sup 161/Gd were determined. The nondestructive neutron-activation determination of gadolinium was possible for gadolinium concentrations where the radial induced-activity distribution was constant. The method for calculating the gamma-ray absorption coefficient was simple and reliable for measurement geometry close to 4pi. Neutron activation results agreed with chemical measurement within the error limits.

In 1992, the U.S. Congress passed legislation to discontinue above- and below-ground testing of nuclear weapons. Because of this, the U.S. Department of Energy (DOE) must rely on laboratory experiments and computer-based calculations to verify the reliability of the nuclear stockpile. The Sandia National Laboratories/New Mexico (SNL/NM) Z machine was developed to support the science-based approach for mimicking nuclear explosions and stockpile stewardship. Plutonium (Pu) isotopes with greater than ninety-eight percent enrichment were used in the experiments. In May 2006, SNL/NM received authority that the Z Machine Isentropic Compression Experiments could commence. Los Alamos National Laboratory (LANL) provided the plutonium targets and loaded the target assemblies provided by SNL/NM. Three experiments were conducted from May through July 2006. The residues from each experiment, which weighed up to 913 pounds, were metallic and were packaged into a 55-gallon drum each. SNL/NM conducts the experiments and provides temporary storage for the drums until shipment to LANL for final waste certification for disposal at the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico. This paper presents a comprehensive approach for documenting generator knowledge for characterization of waste in cooperation with scientists at the two laboratories and addresses a variety of essential topics.

A mechanistic kinetic rate theory model originally developed for the prediction of fission gas behavior in oxide nuclear fuels under steady-state and transient conditions has been assessed to look at its applicability to model fission gas behavior in U-Pu-Zr metallic alloy fuel. In order to capture and validate the underlying physics for irradiated U-Pu-Zr fuels, the mechanistic model was applied to the simulation of fission gas release, fission gas and fission product induced swelling, and the evolution of the gas bubble size distribution in three different fuel zones: the outer {alpha}-U, the intermediate, and the inner {gamma}-U zones. Due to its special microstructural features, the {alpha}-U zone in U-Pu-Zr fuels is believed to contribute the largest fraction of fission gas release among the different fuel zones. It is shown that with the use of small effective grain sizes, the mechanistic model can predict fission gas release that is consistent with (though slightly lower than) experimentally measured data. These simulation results are comparable to the experimentally measured fission gas release since the mechanism of fission gas transport through the densely distributed laminar porosity in the {alpha}-U zone is analogous to the mechanism of fission gas transport through the interconnected gas bubble porosity utilized in the mechanistic model. Detailed gas bubble size distributions predicted with the mechanistic model in both the intermediate zone and the high temperature {gamma}-U zone of U-Pu-Zr fuel are also compared to experimental measurements from available SEM micrographs. These comparisons show good agreements between the simulation results and experimental measurements, and therefore provide crucial guidelines for the selection of key physical parameters required for modeling these two zones. In addition, the results of parametric studies for several key parameters are presented for both the intermediate zone and the {gamma}-U zone simulations. (authors)

Because diffraction measurements are sensitive only to the long range average arrangement of the atoms in the coherent portion of a crystal, complementary local structure measurements are required for a complete understanding of the structure of a complex material. This is particularly an issue in solid solutions where even random distributions of a solute will result in nanometer-scale fluctuations in the local composition. The structure will be further complicated if collective and cooperative phenomena organize the solute distribution via longer range interactions between non-bonded solute sites. If the solute affects the phase stability then the question is raised of whether the atoms in domains with local compositions outside the limits of the bulk phase will rearrange into the structure stable for that composition and temperature or if the resulting stress would prevent such a local phase transition. If the former, then phase separated, heterogeneous structures at or below the diffraction limit will form. This nanometerscale competition between the phase transition and the epitaxial mismatch – exacerbated by the added strain if the transition involves a volume change – raises the potential for the formation of novel structures that do not occur in bulk material, e.g., fcc Fe. This coupling over multiple scales between inhomogeneity ordering, elastic forces, phase competition, and texture in the form of coexisting structures is a hallmark of martensites, a class of complex materials that includes ?-stabilized PuGa and that often exhibit correlated atomic and electronic properties. The enigmatic and extreme nature of Pu is consistent with its exhibiting unusual structural behavior of this type, including nanoscale heterogeneity in ?-stabilized PuGa and its enhanced homogeneity on aging that has been suggested based on earlier X-ray Absorption Fine Structure (XAFS) spectroscopy and x-ray pair distribution function (pdf) measurements. Measurements on a defined set of laboratory-prepared materials now corroborate and better describe this heterogeneity while additional aged samples demonstrate the role of heterogeneity in aging processes in Pu.

Recent deep space missions utilize the thermal output of the radioisotope plutonium-238 as the fuel in the thermal to electrical power system. Since the application of plutonium in its elemental state has several disadvantages, the fuel employed in these deep space power systems is typically in the oxide form such as plutonium-238 dioxide (238PuO2). As an oxide, the processing of the plutonium dioxide into fuel pellets is performed via ''classical'' ceramic processing unit operations such as sieving of the powder, pressing, sintering, etc. Modeling of these unit operations can be beneficial in the understanding and control of processing parameters with the goal of further enhancing the desired characteristics of the 238PuO2 fuel pellets. A finite element model has been used to help identify the time-temperature-stress profile within a pellet during a furnace operation taking into account that 238PuO2 itself has a significant thermal output. Results of the modeling efforts will be discussed.

Spin and orbital and electron correlations are known to be important when treating the high-temperature {delta} phase of plutonium within the framework of density-functional theory (DFT). One of the more successful attempts to model {delta}-Pu within this approach has included condensed-matter generalizations of Hund's three rules for atoms, i.e., spin polarization, orbital polarization, and spin-orbit coupling. Here they perform a quantitative analysis of these interactions relative rank for the bonding and electronic structure in {delta}-Pu within the DFT model. The result is somewhat surprising in that spin-orbit coupling and orbital polarization are far more important than spin polarization for a realistic description of {delta}-Pu. They show that these orbital correlations on their own, without any formation of magnetic spin moments, can account for the low atomic density of the {delta} phase with a reasonable equation-of-state. In addition, this unambiguously non-magnetic (NM) treatment produces a one-electron spectra with resonances close to the Fermi level consistent with experimental valence band photoemission spectra.

Recent deep space missions utilize the thermal output of the radioisotope plutonium-238 as the fuel in the thermal to electrical power system. Since the application of plutonium in its elemental state has several disadvantages, the fuel employed in these deep space power systems is typically in the oxide form such as plutonium-238 dioxide (238PuO2). As an oxide, the processing of the plutonium dioxide into fuel pellets is performed via ''classical'' ceramic processing unit operations such as sieving of the powder, pressing, sintering, etc. Modeling of these unit operations can be beneficial in the understanding and control of processing parameters withmore »the goal of further enhancing the desired characteristics of the 238PuO2 fuel pellets. A finite element model has been used to help identify the time-temperature-stress profile within a pellet during a furnace operation taking into account that 238PuO2 itself has a significant thermal output. Results of the modeling efforts will be discussed.« less

-om Leishmania tarentolae by mung bean nuclease and identification of several additional minicircle sequence££ were cleaved by mung bean nuclease in the presence of formamide, yielding unit length linear molecules was not a requirement for cleavage, as linearized network-derived or cloned minicircles were also cleaved by mung bean

Influence of CdTe thickness on structural and electrical properties of CdTe/CdS solar cells A a b s t r a c ta r t i c l e i n f o Available online xxxx Keywords: Solar cells CdCl2 CdTe Thin absorbers Due to its high scalability and low production cost, CdTe solar cells have shown a very strong

A TRISO-coated fuel thermo-mechanical performance study is performed for the hybrid LIFE engine to test the viability of TRISO particles to achieve ultra-high burnup of a weapons-grade Pu blanket. Our methodology includes full elastic anisotropy, time and temperature varying material properties for all TRISO layers, and a procedure to remap the elastic solutions in order to achieve fast fluences up to 30 x 10{sup 25} n {center_dot} m{sup -2} (E > 0.18 MeV). In order to model fast fluences in the range of {approx} 7 {approx} 30 x 10{sup 25} n {center_dot} m{sup -2}, for which no data exist, careful scalings and extrapolations of the known TRISO material properties are carried out under a number of potential scenarios. A number of findings can be extracted from our study. First, failure of the internal pyrolytic carbon (PyC) layer occurs within the first two months of operation. Then, the particles behave as BISO-coated particles, with the internal pressure being withstood directly by the SiC layer. Later, after 1.6 years, the remaining PyC crumbles due to void swelling and the fuel particle becomes a single-SiC-layer particle. Unrestrained by the PyC layers, and at the temperatures and fluences in the LIFE engine, the SiC layer maintains reasonably-low tensile stresses until the end-of-life. Second, the PyC creep constant, K, has a striking influence on the fuel performance of TRISO-coated particles, whose stresses scale almost inversely proportional to K. Obtaining more reliable measurements, especially at higher fluences, is an imperative for the fidelity of our models. Finally, varying the geometry of the TRISO-coated fuel particles results in little differences in the scope of fuel performance. The mechanical integrity of 2-cm graphite pebbles that act as fuel matrix has also been studied and it is concluded that they can reliable serve the entire LIFE burnup cycle without failure.

In 1992, the U.S. Congress passed legislation to discontinue above- and below-ground testing of nuclear weapons. Because of this, the U.S. Department of Energy (DOE) must rely on laboratory experiments and computer-based calculations to verify the reliability of the nation's nuclear stockpile. The Sandia National Laboratories/New Mexico (SNL/NM) Z machine was developed by the DOE to support its science-based approach to stockpile stewardship. SNL/NM researchers also use the Z machine to test radiation effects on various materials in experiments designed to mimic nuclear explosions. Numerous components, parts, and materials have been tested. These experiments use a variety of radionuclides; however, plutonium (Pu) isotopes with greater than ninety-eight percent enrichment are the primary radionuclides used in the experiments designed for stockpile stewardship. In May 2006, SNL/NM received authority that the Z Machine Isentropic Compression Experiments could commence. Los Alamos National Laboratory (LANL) provided the plutonium targets and loaded the target assemblies, which were fabricated by SNL/NM. LANL shipped the loaded assemblies to SNL/NM for Z machine experiments. Three experiments were conducted from May through July 2006. The residues from each experiment, which weighed up to 913 pounds, were metallic and packaged into a respective 55-gallon drum each. Based on a memorandum of understanding between the two laboratories, LANL provides the plutonium samples and the respective radio-isotopic information. SNL/NM conducts the experiments and provides temporary storage for the drums until shipment to LANL for final waste certification for disposal at the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico. This paper presents a comprehensive approach for documenting generator knowledge for characterization of waste in cooperation with scientists at the two laboratories and addresses a variety of topics such as material control and accountability, safeguards of material, termination of safeguards for eventual shipment from SNL/NM to LANL, associated approvals from DOE-Carlsbad Field Office, which governs WIPP and various notifications. It portrays a comprehensive approach needed for successful completion of a complex project between two national laboratories.

The primary goal of this investigation was to obtain data on the possibility, extent, and characteristics of interaction of Pu(IV) and (VI) with hydroxides and oxides of d-elements and other metals [Al(III), LA(III), and U(VI)] in alkaline media. Such information is important in fundamental understanding of plutonium disposition and behavior in Hanford Site radioactive tank waste sludge. These results supply essential data for determining criticality safety and in understanding transuranic waste behavior in storage, retrieval, and treatment of Hanford Site tank waste.

Plutonium released to the environment may contribute to dose to humans through inhalation or ingestion of contaminated foodstuffs. Plutonium contamination of agricultural plants may result from interception and retention of atmospheric deposition, resuspension of Pu-bearing soil particles to plant surfaces, and root uptake. Plutonium on vegetation surfaces may be transferred to grain surfaces during mechanical harvesting. Data obtained from corn grown near the U.S. Department of Energy's H-Area nuclear fuel chemical separations facility on the Savannah River Site were used to estimate parameters of a simple model of Pu transport in agroecosystems. The parameter estimates for corn were compared to those previously obtained for wheat and soybeans. Despite some differences in parameter estimates among crops, the relative importances of atmospheric deposition, resuspension, and root uptake were similar among crops. For even small deposition rates, the relative importances of processes for Pu contamination of corn grain should be: transfer of atmospheric deposition from vegetation surfaces to grain surfaces during combining greater than resuspension of soil to grain surfaces greater than root uptake. Approximately 3.9 X 10(-5) of a year's atmospheric deposition is transferred to grain. Approximately 6.2 X 10(-9) of the Pu inventory in the soil is resuspended to corn grain, and a further 7.3 X 10(-10) of the soil Pu inventory is absorbed and translocated to grains.

A novel photochemical method of removing reactive fluorides from UF{sub 6} gas has been discovered. This method reduces generated waste to little more than the volume of the removed impurities, minimizes loss of UF{sub 6}, and can produce a recyclable by-product, fluorine gas. In our new method, impure UF{sub 6}, is exposed to ultraviolet light which dissociates the UF{sub 6} to UF{sub 5} and fluorine atom. Impurities which chemically react with UF{sub 5} are reduced and form solid compounds easily removed from the gas while UF{sub 5} is converted back to UF{sub 6}. Proof-of-concept testing involved UF{sub 6} containing NpF{sub 6} and PuF{sub 6} with CO added as a fluorine atom scavenger. In a single photolysis step, greater than 5000-fold reduction of PuF{sub 6} was demonstrated while reducing NpF{sub 6} by more than 40-fold. This process is likely to remove corrosion and fission product fluorides that are more reactive than UF{sub 6} and has been demonstrated without an added fluorine atom scavenger by periodically removing photogenerated fluorine gas. 44 refs., 3 figs., 2 tabs.

A well-homogenized Pu-2 at.% Ga alloy can be retained in the metastable face-centered cubic {delta} phase at room temperature. Ultimately, this metastable {delta} phase will decompose via a eutectoid transformation to the thermodynamically stable monoclinic {alpha} phase and the intermetallic compound Pu{sub 3}Ga over a period of approximately 10,000 years [1]. In addition, these low solute-containing {delta}-phase Pu alloys are metastable with respect to an isothermal martensitic phase transformation to the {alpha}{prime} phase during low temperature excursions [2, 3] and are also metastable with respect to a {delta} {yields} {alpha}{prime} phase transformation with increases in pressure [3-5]. The low temperature {delta} {yields} {alpha}{prime} isothermal martensitic phase transformation in the Pu-2 at.% Ga alloy only goes to {approx}25% completion with the resultant {approx}20 {micro}m long by 2 {micro}m wide lath-shaped {alpha}{prime} particles dispersed within the {delta} matrix. In recently reported studies, Faure et al. [4] have observed a {delta} {yields} {gamma} {yields} {alpha}{prime} pressure-induced phase transformation sequence during a diamond anvil cell investigation and, based on x-ray diffraction and density and compressibility experiments, Harbur [5] has concluded that both {alpha}{prime} and an amorphous phase are present in samples that were pressurized and recovered. In this work, a large volume moissanite anvil cell is constructed to permit the pressurization and recovery of specimens of a size suitable for TEM and electron diffraction studies. The cell, shown in Fig. 1, has an overall diameter of 101.6 mm, a moissanite anvil diameter of 9.00 mm, a culet size of 3 mm, and a spring steel gasket 0.5 mm thick with a hole diameter of 2.5 mm. A 2.3 mm diameter by 100 {micro}m thick sample of {delta}-phase Pu-2 at.% Ga is compressed at a rate of approximately 0.05 GPa/minute to {approx}1 GPa to induce the phase transformation to {alpha}{prime}. Optical microscopy of the recovered specimen reveals a very fine microstructure that appears to be single phase, although the resolution of this technique is insufficient to differentiate between single and multiple phases if the grain size is below approximately 1 {micro}m. X-ray diffraction, using a laboratory Cu K{sub {alpha}} source with wavelength of 1.542{angstrom}, shows the monoclinic reflections from the {alpha}{prime} phase, strong peaks from the aluminum specimen holder, and weak peaks from the face-centered cubic {delta} phase as shown in Fig. 2. The recovered specimen is prepared for TEM and electron diffraction studies as described in Moore et al. [6]. TEM reveals small regions of {delta} phase with a very high dislocation density interspersed between the 10-100's nm {alpha}{prime} grains as shown in Fig. 3. Electron diffraction, shown in the insert in Fig. 3, clearly reveals the presence of the {delta} phase. This microstructure is in contrast to the {alpha}{prime} particles that form as a result of the low-temperature isothermal martensite in which the {alpha}{prime} particles are lath-shaped and significantly larger as shown in the optical micrograph in Fig. 4 of a sample cooled to -120 C and held for 10 hours. In these preliminary results, there is no evidence of either an amorphous phase, as suggested by Harbur [5], or the presence of a {gamma} phase. We expected to observe an amorphous phase based on the similarity of this experiment to that of Harbur [5]. It is possible that the {gamma} phase, as reported by Faure et al. [4], does form as an intermediate, but it is not retained to ambient pressure.

Sodium cooled Fast Reactors (SFR) have been under consideration for production of electricity, fissile material production, and for destruction of transuranics for decades. The neutron economy of a SFR can be operated in one of two ways. One possibility is to operate the reactor in a transuranic burner mode which has been the focus of active R&D in the last 15 years. However, prior to that the focus was on breeding transuranics. This later mode of managing the neutron economy relies on ensuring the maximum fuel utilization possible in such a way as to maximize the amount of plutonium produced per unit of fission energy in the reactor core. The goal of maximizing plutonium production in this study is as fissile feed stock for the production of MOX fuel to be used in Light Water Reactors (LWR). Throughout the l970’s, this fuel cycle scenario was the focus of much research by the Atomic Energy Commission in the event that uranium supplies would be scarce. To date, there has been sufficient uranium to supply the once through nuclear fuel cycle. However, interest in a synergistic relationship Liquid Metal Fast Breeder Reactors (LMFBR) and a consumer LWR fleet persists, prompting this study. This study considered LMFBR concepts with varying additions of axial and radial reflectors. Three scenarios were considered in collaboration with a companion study on the LWR-MOX designs based on plutonium nuclide vectors produced by this study. The first scenario is a LMFBR providing fissile material to make MOX fuel where the MOX part of the fuel cycle is operated in a once-through-then-out mode. The second scenario is the same as the first but with the MOX part of the fuel cycle multi-recycling its own plutonium with LMFBR being used for the make-up feed. In these first two scenarios, plutonium partitioning from the minor actinides (MA) was assumed. Also, the plutonium management strategy of the LMFBR ensured that only the high fissile purity plutonium bred from blankets was sold to the MOX LWRs. The third scenario considered a LMFBR fuel cycle in an expansionary mode where excess bred transuranic material is accumulated for spinning off additional LMFBR cores. In this latter scenario, no plutonium partitioning was considered. After every cycle, transuranic from both driver and blankets is sold to the MOX LWRs. The MA production from LMFBR operated in a Pu-only fuel cycle is roughly only 1% that of the transuranic production rate. This is in contrast to LWR fuel cycles where the MA content in TRU is closer to 10% or more. If such a LMFBR were operated to provide fissile material to a fleet of MOX reactors, then 1 GWe of LMFBR could support between approximately 0.11 and 0.43 GWe of LWR-MOX reactors for a LMFBR conversion ratio between 1.1 and 1.5, if the MOX reactors were operated in a once-through-then out mode. If the plutonium is continuously recycled in the MOX reactors then the support ratio is approximately 1 GWe of LMFBR for between 0.13 and 0.65 GWe of LWR-MOX reactors depending on the LMFBR conversion ratio. Also, it was found that if the LMFBR fleet were operated in a purely expansionary mode, the smallest doubling time achievable would be seven years.

We have examined the relaxation of photoinduced quasiparticles in the heavy-fermion superconductor PuCoGa{sub 5}. The deduced electron-phonon coupling constant is incompatible with the measured superconducting transition temperature T{sub c}, which speaks against phonon-mediated superconducting pairing. Upon lowering the temperature, we observe an order-of-magnitude increase of the quasiparticle relaxation time in agreement with the phonon bottleneck scenario - evidence for the presence of a hybridization gap in the electronic density of states. The modification of photoinduced reflectance in the superconducting state is consistent with the heavy character of the quasiparticles that participate in Cooper pairing. The discovery of relatively high-temperature superconductivity in the Pu-based compounds PuCoGa{sub 5} (T{sub c} = 18.5 K) and PuRhGa{sub 5} (T{sub c} = 8.7 K) has renewed the interest in actinide materials research. The Pu-based superconductors share the HoCoGa{sub 5}-type tetragonal lattice stucture with the Ce-based series of compounds (CeRhIn{sub 5}, CeCoIn{sub 5}, and CeIrIn{sub 5}) commonly referred to as '115' materials. In the Ce-based 115 compounds, CeIrIn{sub 5} (T{sub c} = 0.4 K) and CeCoIn{sub 5} (T{sub c} = 2.3 K), display superconductivity at ambient pressure. Both Ce- and Pu-based 115 compounds display the heavy fermion behavior resulting from the influence of 4f (Ce) and 5f (Pu) electrons. The most intriguing question concerns the origin of superconductivity (SC) in the 115 materials. In the Ce series, the d-wave symmetry of the SC order parameter and the proximity of SC order to magnetism have lead to a widespread belief that the unconventional SC is induced by antiferromagnetic spin fluctuations. In the Pu compounds, two possible scenarios regarding the SC mechanism have been considered: one approach favors a magnetically mediated unconventional SC similar to that in CeCoIn{sub 5}. In the other scenario, the conventional SC is mediated by phonons, where the strength of the electron-phonon (e-ph) coupling {lambda} is the crucial parameter that sets the superconducting transition temperature T{sub c}. In this Letter, we present a measurement of the e-ph coupling constant {lambda} via the pump-probe optical study of the room-temperature relaxation time of photoinduced reflectance. We find that e-ph coupling ({lambda} = 0.2-0.26) is too weak to explain the high T{sub c} of PuCoGa{sub 5} and that phonon-mediated superconductivity is unlikely in this material. Upon lowering the temperature in the normal state (T > T{sub c}), we find an order-of-magnitude increase in the relaxation time consistent with a phonon bottleneck, similar to other heavy-fermion materials, which provides the first optical evidence of the presence of a hybridization gap in the electronic density of states (DOS). Below T{sub c}, the photoinduced response exhibits dramatic changes that we ascribe to the opening of the superconducting (SC) gap at the Fermi level. The observed dynamics confirms that the same quasiparticles detected in the normal state, i.e., the heavy quasiparticles, also participate in the SC pairing. Our study is the first to directly probe the electronic structure of PuCoGa{sub 5} in the SC state and corroborate that fact. Our results are consistent with the theoretical investigations, which find that the electronic structure is dominated by cylindrical sheets of Fermi surfaces with large 5f electron character, suggesting that the delocalized 5f electrons of Pu playa key role in the superconducting pairing.

The empirical relativistic density-dependent, point-coupling energy density functional, adjusted exclusively to experimental binding energies of a large set of deformed nuclei with Aapprox =150-180 and Aapprox =230-250, is tested with spectroscopic data for {sup 166}Er and {sup 240}Pu. Starting from constrained self-consistent triaxial relativistic Hartree-Bogoliubov calculations of binding energy maps as functions of the quadrupole deformation in the beta-gamma plane, excitation spectra and E2 transition probabilities are calculated as solutions of the corresponding microscopic collective Hamiltonian in five dimensions for quadrupole vibrational and rotational degrees of freedom and compared with available data on low-energy collective states.

The 18.5 K superconductor PuCoGa{sub 5} has many unusual properties, including those due to damage induced by self-irradiation. The superconducting transition temperature decreases sharply with time, suggesting a radiation-induced Frenkel defect concentration much larger than predicted by current radiation damage theories. Extended x-ray absorption fine-structure measurements demonstrate that while the local crystal structure in fresh material is well ordered, aged material is disordered much more strongly than expected from simple defects, consistent with strong disorder throughout the damage cascade region. These data highlight the potential impact of local lattice distortions relative to defects on the properties of irradiated materials and underscore the need for more atomic-resolution structural comparisons between radiation damage experiments and theory.

Within the framework of the dinuclear system (DNS) model, production cross sections of new superheavy nuclei with charged numbers Z=108-114 are analyzed systematically. Possible combinations based on the actinide nuclides $^{238}$U, $^{244}$Pu and $^{248,250}$Cm with the optimal excitation energies and evaporation channels are pointed out to synthesize new isotopes which lie between the nuclides produced in the cold fusion and the $^{48}$Ca induced fusion reactions experimentally, which are feasible to be constructed experimentally. It is found that the production cross sections of superheavy nuclei decrease drastically with the charged numbers of compound nuclei. Larger mass asymmetries of the entrance channels enhance the cross sections in 2n-5n channels.

Within the framework of the dinuclear system (DNS) model, production cross sections of new superheavy nuclei with charged numbers Z=108-114 are analyzed systematically. Possible combinations based on the actinide nuclides $^{238}$U, $^{244}$Pu and $^{248,250}$Cm with the optimal excitation energies and evaporation channels are pointed out to synthesize new isotopes which lie between the nuclides produced in the cold fusion and the $^{48}$Ca induced fusion reactions experimentally, which are feasible to be constructed experimentally. It is found that the production cross sections of superheavy nuclei decrease drastically with the charged numbers of compound nuclei. Larger mass asymmetries of the entrance channels enhance the cross sections in 2n-5n channels.

The EP-61 primary containment vessel of the 5320 shipping package has been used for storage and transportation of Pu-238 plutonium oxide heat source material. For storage, the material in its convenience canister called EP-60 is placed in the EP-61 and sealed by two threaded caps with elastomer O-ring seals. When the package is shipped, the outer cap is seal welded to the body. While stored, the EP-61s are placed in a cooling water bath. In preparation for welding, several containers are removed from storage and staged to the welding booth. The significant heat generation of the contents, and resulting rapid rise in component temperature necessitates special handling practices. The test described here was performed to determine the temperature rise with time and peak temperature attained for an EP-61 with 203 watts of internal heat generation, upon its removal from the cooling water bath.

Structural phase transitions on the nanoscale: The crucial pattern in the phase-change materials Ge2Sb2Te5 and GeTe J. Akola1,2 and R. O. Jones1 1Institut für Festkörperforschung, Forschungszentrum to characterize the amorphous structure of the prototype materials Ge2Sb2Te5 and GeTe. In both, there is long

Fast breeder reactors (FBR) nuclear fuel cycle is needed for long-term nuclear sustainability while preventing global warming and maximum utilizing the limited uranium (U) resources. The 'Framework for Nuclear Energy Policy' by the Japanese government on October 2005 stated that commercial FBR deployment will start around 2050 under its suitable conditions by the successive replacement of light water reactors (LWR) to FBR. Even after Fukushima Daiichi Nuclear Power Plant accident which made Japanese tendency slow down the nuclear power generation activities, Japan should have various options for energy resources including nuclear, and also consider the delay of FBR deployment and increase of LWR spent fuel (LWR-SF) storage amounts. As plutonium (Pu) for FBR deployment will be supplied from LWR-SF reprocessing and Japan will not possess surplus Pu, the authors have developed the flexible fuel cycle initiative (FFCI) for the transition from LWR to FBR. The FFCI system is based on the possibility to stored recycled materials (U, Pu)temporarily for a suitable period according to the FBR deployment rate to control the Pu demand/supply balance. This FFCI system is also effective after the Fukushima accident for the reduction of LWR-SF and future LWR-to-FBR transition. (authors)

Plutonium-bearing liquors, including ANL scrap liquors, will be used for development and demonstration of a vertical calciner direct denitration process for conversion of those liquors to stable, storable PuO{sub 2}-rich solids. This test plan is to test with non-radioactive stand-in materials to demonstrate adequate performance of the vertical calciner and ancillary equipment.

The authors have measured the resistivity and thermopower of single crystals as well as polycrystalline pressed powders of the low-dimensional pentatelluride materials: HfTe{sub 5} and ZrTe{sub 5}. They have performed these measurements as a function of temperature between 5K and 320K. In the single crystals there is a peak in the resistivity for both materials at a peak temperature, T{sub p} where T{sub p} {approx} 80K for HfTe{sub 5} and T{sub p} {approx} 145K for ZrTe{sub 5}. Both materials exhibit a large p-type thermopower around room temperature which undergoes a change to n-type below the peak. These data are similar to behavior observed previously in these materials. They have also synthesized pressed powders of polycrystalline pentatelluride materials, HfTe{sub 5} and ZrTe{sub 5}. They have measured the resistivity and thermopower of these polycrystalline materials as a function of temperature between 5K and 320K. For the polycrystalline material, the room temperature thermopower for each of these materials is relatively high, +95 {micro}V/K and +65 {micro}V/K for HfTe{sub 5} and ZrTe{sub 5}, respectively. These values compare closely to thermopower values for single crystals of these materials. At 77 K, the thermopower is +55 {micro}V/K for HfTe{sub 5} and +35 {micro}V/K for ZrTe{sub 5}. In fact, the thermopower for the polycrystals decreases monotonically with temperature to T {approx} 5K, thus exhibiting p-type behavior over the entire range of temperature. As expected, the resistivity for the polycrystals is higher than the single crystal material, with values of 430 m{Omega}-cm and 24 m{Omega}-cm for HfTe{sub 5} and ZrTe{sub 5} respectively, compared to single crystal values of 0.35 m{Omega}-cm (HfTe{sub 5}) and 1.0 m{Omega}-cm (ZrTe{sub 5}). The authors have found that the peak in the resistivity evident in both single crystal materials is absent in these polycrystalline materials. They will discuss these materials in relation to their potential as candidates for thermoelectric applications.

A method of is disclosed improving electrical contact to a thin film of a p-type tellurium-containing II-VI semiconductor comprising: depositing a first undoped layer of ZnTe on a thin film of p-type tellurium containing II-VI semiconductor with material properties selected to limit the formation of potential barriers at the interface between the p-CdTe and the undoped layer, to a thickness sufficient to control diffusion of the metallic-doped ZnTe into the p-type tellurium-containing II-VI semiconductor, but thin enough to minimize affects of series resistance; depositing a second heavy doped p-type ZnTe layer to the first layer using an appropriate dopant; and depositing an appropriate metal onto the outer-most surface of the doped ZnTe layer for connecting an external electrical conductor to an ohmic contact. 11 figs.

In nuclear material processing facilities, it is often necessary to balance the competing demands of accuracy and throughput. While passive neutron multiplicity counting is the preferred method for relatively fast assays of plutonium, the presence of low-Z impurities (fluorine, beryllium, etc.) rapidly erodes the assay precision of passive neutron counting techniques, frequently resulting in unacceptably large total measurement uncertainties. Conversely, while calorimeters are immune to these impurity effects, the long count times required for high accuracy can be a hindrance to efficiency. The higher uncertainties in passive neutron measurements of impure material are driven by the resulting large (>>2) {alpha}-values, defined as the ({alpha},n):spontaneous fission neutron emission ratio. To counter impurity impacts for high-{alpha} materials, a known-{alpha} approach may be adopted. In this method, {alpha} is determined for a single item using a combination of gamma-ray and calorimetric measurements. Because calorimetry is based on heat output, rather than a statistical distribution of emitted neutrons, an {alpha}-value determined in this way is far more accurate than one determined from passive neutron counts. This fixed {alpha} value can be used in conventional multiplicity analysis for any plutonium-bearing item having the same chemical composition and isotopic distribution as the original. With the results of single calorimeter/passive neutron/gamma-ray measurement, these subsequent items can then be assayed with high precision and accuracy in a relatively short time, despite the presence of impurities. A calorimeter-based known-{alpha} multiplicity analysis technique is especially useful when requiring rapid, high accuracy, high precision measurements of multiple plutonium bearing items having a common source. The technique has therefore found numerous applications at the Savannah River Site. In each case, a plutonium (or mixed U/Pu) bearing item is divided into multiple containers. A single item from that batch is then selected for both neutron and calorimetric measurements; all remaining items undergo a neutron measurement only. Using the technique mentioned above, the 'true' {alpha} value determined from the first (calorimeter and passive neutron measured) item is used in multiplicity analysis for all other items in the batch. The justification for using this {alpha} value in subsequent calculations is the assumption that the chemical composition and isotopic distribution of all batch items are the same, giving a constant ({alpha},n):spontaneous fission ratio. This analysis method has been successfully applied to the KIS Facility, significantly improving measurement uncertainties and reducing processing times for numerous items. Comprehensive plans were later developed to extend the use of this method to other applications, including the K-Area Shuffler and the H-Area Pu-Blending Project. While only the feasibility study for the Shuffler has been completed, implementation of the method in the H-Area Pu-Blending Project is currently in progress and has been successfully applied to multiple items. This report serves to document the details of this method in order to serve as a reference for future applications. Also contained herein are specific examples of the application of known-{alpha} multiplicity analysis.

This is a cumulative and final report for Phases I, II and III of this NREL funded project (subcontract # XXL-5-44205-10). The main research activities of this project focused on the open-circuit voltage of the CdTe thin film solar cells. Although, thin film CdTe continues to be one of the leading materials for large-scale cost-effective production of photovoltaics, the efficiency of the CdTe solar cells have been stagnant for the last few years. This report describes and summarizes the results for this 3-year research project.

For the past several years, competing resource demands within BPA have forced the Agency to stretch Operations, Maintenance and Replacement (OM R) resources. There is a large accumulation of tasks that were not accomplished when scheduled. Maintenance and replacements and outages, due to material and equipment failure, appear to be increasing. BPA has made a strategic choice to increase its emphasis on OM R programs by implementing a multi-year, levelized OM R plan which is keyed to high system reliability. This strategy will require a long-term commitment of a moderate increase in staff and dollars allocated to these programs. In an attempt to assess the direction BPA has taken in its OM R programs, a utility comparison team was assembled in early January 1989. The team included representatives from BPA's Management Analysis, Internal Audit and Financial Management organizations, and operation and maintenance program areas. BPA selected four utilities from a field of more than 250 electric utilities in the US and Canada. The selection criteria generally pertained to size, with key factors including transformation capacity, load, gross revenue, and interstate transmission and/or marketing agreements, and their OM R programs. Information was gathered during meetings with managers and technical experts representing the four utilities. Subsequent exchanges of information also took place to verify findings. The comparison focused on: Transmission operations and maintenance program direction and emphasis; Organization, management and implementation techniques; Reliability; and Program costs. 2 figs., 21 tabs.

Optical in-well pumped mid-infrared vertical external cavity surface emitting lasers based on PbTe quantum wells embedded in CdTe barriers are realized. In contrast to the usual ternary barrier materials of lead salt lasers such as PbEuTe of PbSrTe, the combination of narrow-gap PbTe with wide-gap CdTe offers an extremely large carrier confinement, preventing charge carrier leakage from the quantum wells. In addition, optical in-well pumping can be achieved with cost effective and readily available near infrared lasers. Free carrier absorption, which is a strong loss mechanism in the mid-infrared, is strongly reduced due to the insulating property of CdTe. Lasing is observed from 85?K to 300?K covering a wavelength range of 3.3–4.2??m. The best laser performance is achieved for quantum well thicknesses of 20?nm. At low temperature, the threshold power is around 100 mW{sub P} and the output power more than 700 mW{sub P}. The significance of various charge carrier loss mechanisms are analyzed by modeling the device performance. Although Auger losses are quite low in IV–VI semiconductors, an Auger coefficient of C{sub A}?=?3.5?×?10{sup ?27} cm{sup 6} s{sup ?1} was estimated for the laser structure, which is attributed to the large conduction band offset.

This report summarizes the evaluations conducted during Phase 1C of the Pu Disposition Study have provided further results which reinforce the conclusions reached during Phase 1A & 1B: These conclusions clearly establish the benefits of the fission option and the use of the ABWR as a reliable, proven, well-defined and cost-effective means available to disposition the weapons Pu. This project could be implemented in the near-term at a cost and on a schedule being validated by reactor plants currently under construction in Japan and by cost and schedule history and validated plans for MOX plants in Europe. Evaluations conducted during this phase have established that (1) the MOX fuel is licensable based on existing criteria for new fuel with limited lead fuel rod testing, (2) that the applicable requirements for transport, handling and repository storage can be met, and (3) that all the applicable safeguards criteria can be met.

Possible fluctuation in the delayed neutron yields (DNYs) in the resonance region was predicted on the basis of experimental data of mass distribution of fission fragments at resonances. Analyzed according to the multimodal random neck rupture model of fission, the small variations in the experimental mass distribution were attributed to fluctuations in the branching ratios to different modes of fission. Using the results of analysis of measured data for {sup 235}U and {sup 239}Pu, the DNYs were calculated for each resonance by the summation method, considering 271 precursors and evaluated data of delayed neutron emission probability. It was found that the DNYs should have local dips for {sup 235}U and spikes for {sup 239}Pu at resonances.

CIELO (Collaborative International Evaluated Library Organization) provides a new working paradigm to facilitate evaluated nuclear reaction data advances. It brings together experts from across the international nuclear reaction data community to identify and document discrepancies among existing evaluated data libraries, measured data, and model calculation interpretations, and aims to make progress in reconciling these discrepancies to create more accurate ENDF-formatted files. The focus will initially be on a small number of the highest-priority isotopes, namely 1H, 16O, 56Fe, 235,238U, and 239Pu. This paper identifies discrepancies between various evaluations of the highest priority isotopes, and was commissioned by the OECD's Nuclear Energy Agency WPEC (Working Party on International Nuclear Data Evaluation Co-operation) during a meeting held in May 2012. The evaluated data for these materials in the existing nuclear data libraries — ENDF/B-VII.1, JEFF-3.1, JENDL-4.0, CENDL-3.1, ROSFOND, IRDFF 1.0 — are reviewed, discrepancies are identified, and some integral properties are given. The paper summarizes a program of nuclear science and computational work needed to create the new CIELO nuclear data evaluations.

In November 2008, the Institute of Nuclear Materials Management (INMM) and the European Safeguards Research and Development Association (ESARDA) co-hosted the International Workshop on Gamma Spectrometry Analysis Codes for U and Pu Isotopics at the Oak Ridge National Laboratory (ORNL). This workshop was conducted in response to needs expressed by the international safeguards community to understand better the capabilities and limitations of the codes; to ensure these codes are sustained; and to ensure updates or revisions are performed in a controlled manner. The workshop was attended by approximately 100 participants. The participants included code developers, code suppliers, safeguards specialists, domestic and international inspectors, process operators, regulators, and programme sponsors from various government agencies. The workshop provided a unique opportunity for code developers, commercial distributors and end users to interact in a hands-on laboratory environment to develop solutions for programmatic and technical issues associated with the various codes. The workshop also provided an international forum for discussing development of an internationally accepted standard test method. This paper discusses the organization of the workshop, its goals and objectives and feedback received from the participants. The paper also describes the significance of the working group's contribution to improving codes that are commonly used during inspections to verify that nuclear facilities are compliant with treaty obligations that ensure nuclear fuel cycle facilities are used for peaceful purposes.

An 8-group representation of relative delayed neutron yields was obtained for epithermal neutron induced fission of sup 2 sup 3 sup 5 U and sup 2 sup 3 sup 9 Pu. These data were compared with ENDF/B-VI data in terms of the average half- life of the delayed neutron precursors and on the basis of the dependence of reactivity on the asymptotic period.

In the presence of hydrogen (H{sub 2}), the synthetic chelating agent ethylenediaminetetraacetate (EDTA), and the electron shuttle anthraquinone-2,6-disulfonate (AQDS), the dissimilatory metal-reducing bacteria (DMRB) Shewanella oneidensis and Geobacter sulfurreducens both reductively solubilized 100% of added 0.5 mM plutonium (IV) hydrous oxide (Pu(IV)O{sub 2} {lg_bullet} xH{sub 2}O{sub (am)}) in {approx}24 h at pH 7 in a non-complexing buffer. In the absence of AQDS, bioreduction was much slower ({approx}22 days) and less extensive ({approx}83-94%). In the absence of DMRB but under comparable conditions, 89% (without AQDS) to 98% (with AQDS) of added 0.5 mM PuO{sub 2} {lg_bullet} xH{sub 2}O{sub (am)} was reductively solubilized over 418 days. Under comparable conditions but in the absence of EDTA, <0.001% of the 0.5 mM PuO{sub 2} {lg_bullet} xH{sub 2}O{sub (am)} was solubilized, with or without bacteria. However, Pu(aq) increased by as much as an order of magnitude in some EDTA-free treatments, both biotic and abiotic, and increases in solubility were associated with the production of both Pu(OH)3(am) and Pu(III)(aq). Incubation with DMRB in the absence of EDTA increased the polymeric and crystalline content of the PuO{sub 2} {lg_bullet} xH{sub 2}O{sub (am)} and also decreased Pu solubility in 6-N HCl. Results from an in vitro assay demonstrated electron transfer to PuO{sub 2} {lg_bullet} xH{sub 2}O{sub (am)} from the S. oneidensis outer-membrane c-type cytochrome MtrC, and EDTA increased the oxidation of MtrC by PuO{sub 2} {lg_bullet} xH{sub 2}O{sub (am)}. Our results suggest that PuO{sub 2} {lg_bullet} xH{sub 2}O{sub (am)} biotic and abiotic reduction and solubilization may be important in anoxic, reducing environments, especially where complexing ligands and electron shuttling compounds are present.

The recent developments in studies of TeV radiation from blazars are highlighted and the implications of these results for derivation of cosmologically important information about the cosmic infrared background radiation are discussed.

This summary of the TeV33 working group at Snowmass reports on work in the areas of Tevatron store parameters, the beam-beam interaction, Main Injector intensity (slip stacking), antiproton production, and electron cooling.

Materials are desperately needed for cryogenic solid state refrigeration. We have investigated nanostructured Bi-Te alloys for their potential use in Ettingshausen refrigeration to liquid nitrogen temperatures. These alloys form alternating layers of Bi{sub 2} and Bi{sub 2}Te{sub 3} blocks in equilibrium. The composition Bi{sub 4}Te{sub 3} was identified as having the greatest potential for having a high Ettingshausen figure of merit. Both single crystal and polycrystalline forms of this material were synthesized. After evaluating the Ettingshausen figure of merit for a large, high quality polycrystal, we simulated the limits of practical refrigeration in this material from 200 to 77 K using a simple device model. The band structure was also computed and compared to experiments. We discuss the crystal growth, transport physics, and practical refrigeration potential of Bi-Te alloys.

Recycling end-of-life cadmium telluride (CdTe) photovoltaic (PV) modules may enhance the competitive advantage of CdTe PV in the marketplace, but the experiences of industries with comparable Environmental, Health and Safety (EH&S) challenges suggest that collection and recycling costs can impose significant economic burdens. Customer cooperation and pending changes to US Federal law may improve recycling economics.

The isotopic composition of Pu in soils on and near the Idaho National Engineering and Environmental Laboratory (INEEL) has been determined in order to apportion the sources of the Pu into those derived from stratospheric fallout, regional fallout from the Nevada Test Site (NTS), and facilities on the INEEL site. Soils collected offsite in Idaho, Montana, and Wyoming were collected to further characterize NTS fallout in the region. In addition, measurements of {sup 237}Np and {sup 137}Cs were used to further identify the source of the Pu from airborne emissions at the Idaho Chemical Processing Plant (ICPP) or fugitive releases from the Subsurface Disposal Area (SDA) in the Radioactive Waste Management Complex (RWMC). There is convincing evidence from this study that {sup 241}Am, in excess of that expected from weapons-grade Pu, constituted a part of the buried waste at the SDA that has subsequently been released to the environment. Measurements of {sup 236}U in waters from the Snake River Plain aquifer and a soil core near the ICPP suggest that this radionuclide may be a unique interrogator of airborne releases from the ICPP. Neptunium-237 and {sup 238}Pu activities in INEEL soils suggest that airborne releases of Pu from the ICPP, over its operating history, may have recently been overestimated.

The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) and first-principles calculations. The experiments show that, surprisingly, although SnTe is closer to the ferroelectric instability, phonon spectra in PbTe exhibit a more anharmonic character. This behavior is reproduced in first-principles calculations of the temperature-dependent phonon self-energy. Our simulations reveal how the nesting of phonon dispersions induces prominent features in the self-energy, which account for the measured INS spectra and their temperature dependence. We establish that the phase-space for three-phonon scattering processes, rather than just the proximity to the lattice instability, is the mechanism determining the complex spectrum of the transverse-optical ferroelectric mode.

The investigation on the effect of confining potential like isotropic harmonic oscillator type potential on the binding and the Coulomb interaction energy of the double acceptors in the presence of magnetic field in a Cd{sub 1?x}Mn{sub x}Te/CdTe Spherical Quantum Dot has been made for the Mn ion composition x=0.3 and compared with the results obtained from the square well type potential using variational procedure in the effective mass approximation.

Micro-Raman spectroscopy of mechanically exfoliated few-quintuple layers of Bi2Te3, Bi2Se3, and Sb2-like" exfoliated few-quintuple layers of Bi2Te3, Bi2Se3, and Sb2Te3. It is found that crystal symmetry breaking

We present evaluations of the prompt fission neutron spectrum (PFNS) of ²³?Pu induced by 500 keV neutrons, and associated covariances. In a previous evaluation by Talou et al. 2010, surprisingly low evaluated uncertainties were obtained, partly due to simplifying assumptions in the quantification of uncertainties from experiment and model. Therefore, special emphasis is placed here on a thorough uncertainty quantification of experimental data and of the Los Alamos model predicted values entering the evaluation. In addition, the Los Alamos model was extended and an evaluation technique was employed that takes into account the qualitative differences between normalized model predicted valuesmore »and experimental shape data. These improvements lead to changes in the evaluated PFNS and overall larger evaluated uncertainties than in the previous work. However, these evaluated uncertainties are still smaller than those obtained in a statistical analysis using experimental information only, due to strong model correlations. Hence, suggestions to estimate model defect uncertainties are presented, which lead to more reasonable evaluated uncertainties. The calculated keff of selected criticality benchmarks obtained with these new evaluations agree with each other within their uncertainties despite the different approaches to estimate model defect uncertainties. The keff one standard deviations overlap with some of those obtained using ENDF/B-VII.1, albeit their mean values are further away from unity. Spectral indexes for the Jezebel critical assembly calculated with the newly evaluated PFNS agree with the experimental data for selected (n,?) and (n,f) reactions, and show improvements for high-energy threshold (n,2n) reactions compared to ENDF/B-VII.1.« less

Bi-Te-based thermoelectric (TE) alloys are excellent candidates for power generation modules. We are interested in reliable TE modules for long-term use at or below 200 C. It is known that the metallurgical characteristics of TE materials and of interconnect components affect the performance of TE modules. Thus, we have conducted an extensive scientific investigation of several commercial TE modules to determine whether they meet our technical requirements. Our main focus is on the metallurgy and thermal stability of (Bi,Sb){sup 2}(Te,Se){sup 3} TE compounds and of other materials used in TE modules in the temperature range between 25 C and 200 C. Our study confirms the material suite used in the construction of TE modules. The module consists of three major components: AlN cover plates; electrical interconnects; and the TE legs, P-doped (Bi{sub 8}Sb{sub 32})(Te{sub 60}) and N-doped (Bi{sub 37}Sb{sub 3})(Te{sub 56}Se{sub 4}). The interconnect assembly contains Sn (Sb {approx} 1wt%) solder, sandwiched between Cu conductor with Ni diffusion barriers on the outside. Potential failure modes of the TE modules in this temperature range were discovered and analyzed. The results show that the metallurgical characteristics of the alloys used in the P and N legs are stable up to 200 C. However, whole TE modules are thermally unstable at temperatures above 160 C, lower than the nominal melting point of the solder suggested by the manufacture. Two failure modes were observed when they were heated above 160 C: solder melting and flowing out of the interconnect assembly; and solder reacting with the TE leg, causing dimensional swelling of the TE legs. The reaction of the solder with the TE leg occurs as the lack of a nickel diffusion barrier on the side of the TE leg where the displaced solder and/or the preexisting solder beads is directly contact the TE material. This study concludes that the present TE modules are not suitable for long-term use at temperatures above 160 C due to the reactivity between the Sn-solder and the (Bi,Sb){sup 2}(Te,Se){sup 3} TE alloys. In order to deploy a reliable TE power generator for use at or below 200 C, alternate interconnect materials must be used and/or a modified module fabrication technique must be developed.

This paper reports the results from three targeted searches of Milagro TeV sky maps: two extragalactic point source lists and one pulsar source list. The first extragalactic candidate list consists of 709 candidates selected from the Fermi-LAT 2FGL catalog. The second extragalactic candidate list contains 31 candidates selected from the TeVCat source catalog that have been detected by imaging atmospheric Cherenkov telescopes (IACTs). In both extragalactic candidate lists Mkn 421 was the only source detected by Milagro. This paper presents the Milagro TeV flux for Mkn 421 and flux limits for the brighter Fermi-LAT extragalactic sources and for all TeVCat candidates. The pulsar list extends a previously published Milagro targeted search for Galactic sources. With the 32 new gamma-ray pulsars identified in 2FGL, the number of pulsars that are studied by both Fermi-LAT and Milagro is increased to 52. In this sample, we find that the probability of Milagro detecting a TeV emission coincident with a pulsar increase...

A new lattice for 3 TeV c.o.m. energy with {beta}* = 5mm was developed which follows the basic concept of the earlier 1.5 TeV design but uses quad triplets for the final focus in order to keep the maximum magnet strength and aperture close to those in 1.5 TeV case. Another difference is employment of combined-function magnets with the goal to lower heat deposition in magnet cold mass and to eliminate bending field free regions which produce 'hot spots' of neutrino radiation that can be an issue at higher energy. The proposed lattice is shown to satisfy the requirements on luminosity, dynamic aperture and momentum acceptance.

A neutron or proton excess in nuclei leads to an isovector-vector mean-field which, through its coupling to the quarks in a bound nucleon, implies a shift in the quark distributions with respect to the Bjorken scaling variable. We show that this result leads to an additional correction to the NuTeV measurement of sin^2(Theta_W). The sign of this correction is largely model independent and acts to reduce their result. Explicit calculation within a covariant and confining Nambu--Jona-Lasinio model predicts that this vector field correction accounts for approximately two-thirds of the NuTeV anomaly. We are therefore led to offer a new interpretation of the NuTeV measurement, namely, that it is further evidence for the medium modification of the bound nucleon wavefunction.

A neutron or proton excess in nuclei leads to an isovector-vector mean field which, through its coupling to the quarks in a bound nucleon, implies a shift in the quark distributions with respect to the Bjorken scaling variable. We show that this result leads to an additional correction to the NuTeV measurement of sin{sup 2}theta{sub W}. The sign of this correction is largely model independent and acts to reduce their result. Explicit calculation in nuclear matter within a covariant and confining Nambu-Jona-Lasinio model predicts that this vector field correction may account for a substantial fraction of the NuTeV anomaly. We are therefore led to offer a new interpretation of the NuTeV measurement, namely, that it provides further evidence for the medium modification of the bound nucleon wave function.

The Material Identification and Surveillance (MIS) project sponsored a literature search on the effects of radiation on salts, with focus on alkali chlorides. The goal of the survey was to provide a basis for estimating the magnitude of {alpha} radiation effects on alkali chlorides that can accompany plutonium oxide (PuO{sub 2}) into storage. Chloride radiolysis can yield potentially corrosive gases in plutonium storage containers that can adversely affect long-term stability. This literature search was primarily done to provide a tutorial on this topic, especially for personnel with nonradiation chemistry backgrounds.

To obtain the resonance parameters in a single energy range up to 2.5 keV neutron energy and the corresponding covariance matrix, a reevaluation of 239Pu was performed with the analysis code SAMMY. The most recent experimental data were analyzed in the energy range thermal to 2.5 keV. The experimental data were renormalized, aligned on a common energy scale, and corrected for residual background. Average neutron transmission and cross sections calculated with the new resonance parameters were compared to the corresponding experimental data and to ENDF/B-VI.

If Lorentz invariance is broken at an energy scale Eq, as has recently been suggested in the context of attempts to quantize gravity, the kinematics of photon-photon collisions would be profoundly affected at lower energies. Specifically, electron-positron pair creation on soft photons may be forbidden at photon energies as low as 30 TeV times square root of (Eq/10**17 GeV) and the Universe would then be transparent to high energy photons. The proposition that Lorentz invariance is broken may be falsified by the techniques of TeV astronomy.

This paper reports on one of the most promising new technologies for improving the qualify of radiation therapy, the use of real-time systems to produce portal images. In the authors' approach, they are constructing a linear array of 256 CdTe photovoltaic detectors attached to a very compact linear scanner, all of which will be mounted in a cassette shaped package to be located under the patient table. The high stopping power of the CdTe allows a high contrast image to be made using only a single Linac pulse per line, resulting in a high contrast image in under 5 seconds.

Direct measurements of the photoinduced magnetization in EuTe, using a two color pump-and-probe technique, are presented. The photoinduced effect was pumped using photons of above-the-bandgap energy, and detected by the Faraday rotation of a probe beam of energy below-the-bandgap. The photoinduced Faraday rotation changes sign, as expected from our model for the optically induced magnetic polaron. The EuTe spin-flop transition at low fields is also detected as a sharp step in the photoinduced Faraday rotation, and its observation provides additional supports for the photoinduced polaron model.

We irradiate a ZnTe single crystal with 10-fs laser pulses at a repetition rate of 80?MHz and investigate its resulting gradual modification by means of coherent-phonon spectroscopy. We observe the emergence of a phonon mode at about 3.6?THz whose amplitude and lifetime grow monotonously with irradiation time. The speed of this process depends sensitively on the pump-pulse duration. Our observations strongly indicate that the emerging phonon mode arises from a Te phase induced by multiphoton absorption of incident laser pulses. A potential application of our findings is laser-machining of microstructures in the bulk of a ZnTe crystal, a highly relevant electrooptic material.

Solar Energy Materials & Solar Cells 91 (2007) 1388­1391 Bifacial configurations for CdTe solar We present a different back contact for CdTe solar cell by the application of only a transparent that acts as a free-Cu stable back contact and at the same time allows to realize bifacial CdTe solar cells

.9°, the Cygnus region of the galaxy becomes the most luminous source of TeV gamma rays in the Northern skySurveying the TeV Sky with Milagro C.P. Lansdell for the Milagro Collaboration University sky. In addition to detecting the known TeV sources of the Crab Nebula and Markarian 421, Milagro has

The objective of this work is to determine the appropriate extrusion conditions of cast Bi?Te? alloys via equal channel angular extrusion (ECAE) to produce material that has a fine grain size (5~30[]m), uniform grain morphology and low grain...

A unifying theme of this conference was the use of different approaches to understand astrophysical sources of energetic particles in the TeV range and above. In this summary I review how gamma-ray astronomy, neutrino astronomy and (to some extent) gravitational wave astronomy provide complementary avenues to understanding the origin and role of high-energy particles in energetic astrophysical sources.

Two-dimensional Monte Carlo of the total pair distribution functions g(r) is determined for Se{sub 80}Te{sub 20} and Se{sub 80}Te{sub 15}Sb{sub 5} alloys, and then it used to assemble the three-dimensional atomic configurations using the reverse Monte Carlo simulation. The partial pair distribution functions g{sub ij}(r) indicate that the basic structure unit in the Se{sub 80}Te{sub 15}Sb{sub 5} glass is di-antimony tri-selenide units connected together through Se-Se and Se-Te chain. The structure of Se{sub 80}Te{sub 20} alloys is a chain of Se-Te and Se-Se in addition to some rings of Se atoms.

We present new results from our studies of defects in current single-crystal CdZnTe material. Our previous measurements, carried out on thin ({approx}1 mm) and long (>12 mm) CZT detectors, indicated that small (1-20 {micro}m) Te inclusions can significantly degrade the device's energy resolution and detection efficiency. We are conducting detailed studies of the effects of Te inclusions by employing different characterization techniques with better spatial resolution, such as quantitative fluorescence mapping, X-ray micro-diffraction, and TEM. Also, IR microscopy and gamma-mapping with pulse-shape analysis with higher spatial resolution generated more accurate results in the areas surrounding the micro-defects (Te inclusions). Our results reveal how the performance of CdZnTe detectors is influenced by Te inclusions, such as their spatial distribution, concentration, and size. We also discuss a model of charge transport through areas populated with Te inclusions.

High Efficiency CdTe/CdS Thin Film Solar Cells Prepared by Treating CdTe Films with a Freon Gas process. A further simplification has been done by substituting the CdCl2 step by treating CdTe films to treat CdTe. In this case CdCl2 vapor is obtained by a source facing the CdTe film or conveyed from

Operations and maintenance costs for offshore wind plants are significantly higher than the current costs for land-based (onshore) wind plants. One way to reduce these costs would be to implement a structural health and prognostic management (SHPM) system as part of a condition based maintenance paradigm with smart load management and utilize a state-based cost model to assess the economics associated with use of the SHPM system. To facilitate the development of such a system a multi-scale modeling approach developed in prior work is used to identify how the underlying physics of the system are affected by the presence of damage and faults, and how these changes manifest themselves in the operational response of a full turbine. This methodology was used to investigate two case studies: (1) the effects of rotor imbalance due to pitch error (aerodynamic imbalance) and mass imbalance and (2) disbond of the shear web; both on a 5-MW offshore wind turbine in the present report. Based on simulations of damage in the turbine model, the operational measurements that demonstrated the highest sensitivity to the damage/faults were the blade tip accelerations and local pitching moments for both imbalance and shear web disbond. The initial cost model provided a great deal of insight into the estimated savings in operations and maintenance costs due to the implementation of an effective SHPM system. The integration of the health monitoring information and O&M cost versus damage/fault severity information provides the initial steps to identify processes to reduce operations and maintenance costs for an offshore wind farm while increasing turbine availability, revenue, and overall profit.

The objective of this three year effort has been to develop an improved materials technology and fabrication process for limited volume production of 1 ft{sup 2} and 4 ft{sup 2} CdS/CdTe photovoltaic modules. The module stability objective by the end of this three year subcontract was to develop techniques to provide ten year life exploration with no greater than 10% degradation. In order to achieve these efficiency and stability objectives, the research program has been separated into tasks including: (1) analysis and characterization of CdS/CdTe Devices; (2) performance optimization on small cells; (3) encapsulation and stability testing; and (4) module efficiency optimization. 27 refs., 18 figs., 3 tabs.

Growth, fabrication and characterization of indium-doped cadmium manganese telluride (CdMnTe)radiation detectors have been described. Alpha-particle spectroscopy measurements and time resolved current transient measurements have yielded an average charge collection efficiency approaching 100 %. Spatially resolved charge collection efficiency maps have been produced for a range of detector bias voltages. Inhomogeneities in the charge transport of the CdMnTe crystals have been associated with chains of tellurium inclusions within the detector bulk. Further, it has been shown that the role of tellurium inclusions in degrading chargecollection is reduced with increasing values of bias voltage. The electron transit time was determined from time of flight measurements. From the dependence of drift velocity on applied electric field the electron mobility was found to be n = (718 55) cm2/Vs at room temperature.

Milagrito, a detector sensitive to very high energy gamma rays, monitored the northern sky from February 1997 through May 1998. With a large field of view and a high duty cycle, this instrument was well suited to perform a search for TeV gamma-ray bursts (GRBs). We report on a search made for TeV counterparts to GRBs observed by BATSE. BATSE detected 54 GRBs within the field of view of Milagrito during this period. An excess of events coincident in time and space with one of these bursts, GRB 970417a, was observed by Milagrito. The excess has a chance probability of $2.8 \\times 10^{-5}$ of being a fluctuation of the background. The probability for observing an excess at least this large from any of the 54 bursts is $1.5 \\times 10^{-3}$. No significant correlations were detected from the other bursts.

Milagrito, a detector sensitive to very high energy gamma rays, monitored the northern sky from February 1997 through May 1998. With a large field of view and a high duty cycle, this instrument was well suited to perform a search for TeV gamma-ray bursts (GRBs). We report on a search made for TeV counterparts to GRBs observed by BATSE. BATSE detected 54 GRBs within the field of view of Milagrito during this period. An excess of events coincident in time and space with one of these bursts, GRB 970417a, was observed by Milagrito. The excess has a chance probability of $2.8 \\times 10^{-5}$ of being a fluctuation of the background. The probability for observing an excess at least this large from any of the 54 bursts is $1.5 \\times 10^{-3}$. No significant correlations were detected from the other bursts.

Time-temperature-transformation (TTT) diagrams for the {delta} {yields} {alpha}{prime} transformation in a number of Pu-Ga alloys were first reported in 1975 by Orme et al. Unlike typical single-C curve kinetics observed in most isothermal martensitic transformations, the Pu-1.9 at.% Ga alloy exhibits two noses, and thus double-C curve kinetics. The authors attributed the occurrence of the double C to a difference in mechanism: a massive transformation for the upper C and a martensitic transformation for the lower C. Since that time, the nature, and the existence of the double C have received only limited attention. The results of Deloffre et al. suggest a confirmation of this behavior, but the fundamental origin of the double C remains unknown. Here, we apply differential scanning calorimetry (DSC) as an alternative approach to acquiring the TTT data and our experimental evidence suggests a confirmation of the double-C behavior after 18 hours of isothermal hold time. In addition, we report three exothermic peaks corresponding to transformations during cooling at 20 C/min prior to the isothermal holds. These three peaks are reproducible and suggest a number of possibilities for the origin of the unique kinetics: {alpha}{prime} forms with different morphologies, or from different embryos in the upper and lower C curves; {alpha}{prime} forms directly in one C curve and forms via an intermediate phase in the other C curve; the two C curves result from {alpha}{prime} forming by two or more distinct mechanisms (e.g., massive and martensitic transformations).

The Milagro water Cherenkov detector near Los Alamos, New Mexico, has been operated as a sky monitor at energies of a few TeV between February 1997 and April 1998. Serving as a test run for the full Milagro detector, Milagrito has taken data during the strong and long-lasting 1997 flare of Mrk 501. We present results from the analysis of Mrk 501 and compare the excess and background rates with expectations from the detector simulations.

The Milagro water Cherenkov detector near Los Alamos, New Mexico, has been operated as a sky monitor at energies of a few TeV between February 1997 and April 1998. Serving as a test run for the full Milagro detector, Milagrito has taken data during the strong and long-lasting 1997 flare of Mrk 501. We present results from the analysis of Mrk 501 and compare the excess and background rates with expectations from the detector simulations.

The directional correlation of coincident ..gamma.. transitions in /sup 127/Te has been measured following the ..beta../sup -/ decay of /sup 127/Sb (T/sub 1/2/ = 3.9 d) using Ge(Li)-Ge(Li) and Ge(Li)-NaI(T1) gamma spectrometers. Measurements have been carried out for 14 gamma cascades resulting in the determination of multipole mixing ratios delta(E2/M1) for 15 ..gamma.. transitions. The present results permitted a definite spin assignment of (7/2) for the 785 keV level and confirmation of several previous assignments to other levels in /sup 127/Te. The g factor of the 340 keV ((9/2)/sup -/) level has also been measured using the integral perturbed angular correlation method in the hyperfine magnetic field of a Te in Ni matrix. The results of the g factor as well as the mixing ratio for the 252 keV ((9/2)/sup -/..-->..(11/2)/sup -/) transition support the earlier interpretation of this state as an anomalous coupling state.

Contrary to the common lore based on naive dimensional analysis, the seesaw scale for neutrino masses can be naturally in the TeV range, with small parameters coming from radiative corrections. We present one such class of type-I seesaw models, based on the left-right gauge group $SU(2)_L\\times SU(2)_R\\times U(1)_{B-L}$ realized at the TeV scale, which fits the observed neutrino oscillation parameters as well as other low energy constraints. We discuss how the small parameters of this scenario can arise naturally from one loop effects. The neutrino fits in this model use quasi-degenerate heavy Majorana neutrinos, as also required to explain the matter-antimatter asymmetry in our Universe via resonant leptogenesis mechanism. We discuss the constraints implied by the dynamics of this mechanism on the mass of the right-handed gauge boson in this class of models with enhanced neutrino Yukawa couplings compared to the canonical seesaw model and find a lower bound of $m_{W_R}\\geq 9.9$ TeV for successful leptogenesi...

The main focus of the work at NREL was on the development of Cu-doped ZnTe contacts to CdTe solar cells in the substrate configuration. The work performed under the CRADA utilized the substrate device structure used at NREL previously. All fabrication was performed at NREL. We worked on the development of Cu-doped ZnTe as well as variety of other contacts such as Sb-doped ZnTe, CuxTe, and MoSe2. We were able to optimize the contacts to improve device parameters. The improvement was obtained primarily through increasing the open-circuit voltage, to values as high as 760 mV, leading to device efficiencies of 7%.

The goal of the program was to develop single crystal CdTe-based top cells grown on Si solar cells as a platform for the subsequent manufacture of high efficiency tandem cells for CPV applications. The keys to both the single junction and the tandem junction cell architectures are the ability to grow high quality single-crystal CdTe and CdZnTe layers on p-type Si substrates, to dope the CdTe and CdZnTe controllably, both n and p-type, and to make low resistance ohmic front and back contacts. EPIR demonstrated the consistent MBE growth of CdTe/Si and CdZnTe/Si having high crystalline quality despite very large lattice mismatches; epitaxial CdTe/Si and CdZnTe/Si consistently showed state-of-the-art electron mobilities and good hole mobilities; bulk minority carrier recombination lifetimes of unintentionally p-doped CdTe and CdZnTe grown by MBE on Si were demonstrated to be consistently of order 100 ns or longer; desired n- and p-doping levels were achieved; solar cell series specific resistances <10 ?-cm2 were achieved; A single-junction solar cell having a state-of-the-art value of Voc and a unverified 16.4% efficiency was fabricated from CdZnTe having a 1.80 eV bandgap, ideal for the top junction in a tandem cell with a Si bottom junction.

The detection by the HESS atmospheric Cerenkov telescope of fourteen new sources from the Galactic plane makes it possible to estimate the contribution of unresolved sources like those detected by HESS to the diffuse Galactic emission measured by the Milagro Collaboration. The number-intensity relation and the luminosity function for the HESS source population are investigated. By evaluating the contribution of such a source population to the diffuse emission we conclude that a significant fraction of the TeV energy emission measured by the Milagro experiment could be due to unresolved sources like HESS sources. Predictions concerning the number of sources which Veritas, Milagro, and HAWC should detect are also given.

The detection by the HESS atmospheric Cerenkov telescope of fourteen new sources from the Galactic plane makes it possible to estimate the contribution of unresolved sources like those detected by HESS to the diffuse Galactic emission measured by the Milagro Collaboration. The number-intensity relation and the luminosity function for the HESS source population are investigated. By evaluating the contribution of such a source population to the diffuse emission we conclude that a significant fraction of the TeV energy emission measured by the Milagro experiment could be due to unresolved sources like HESS sources. Predictions concerning the number of sources which Veritas, Milagro, and HAWC should detect are also given.

OG 2.3.07 Search for Short Duration Bursts of TeV Gamma Rays with the Milagrito Telescope Gus for short duration bursts of TeV photons. Such bursts may result from "traditional" gamma-ray bursts to gamma-ray bursts, the final stages of black hole evaporation) the most compelling reason may

that observes very high energy gamma rays (100 GeV to 100 TeV) using the water-Cerenkov technique Mexico, Milagro observes most of the Northern Hemisphere over the course of a day. The high duty cycleV candidates. Active galaxies have been observed to be highly variable at TeV energies. To test for episodic

NUMERICAL MODELING OF CIGS AND CdTe SOLAR CELLS: SETTING THE BASELINE M. Gloeckler, A important complications that are often found in experimental CIGS and CdTe solar cells. 1. INTRODUCTION Numerical modeling of polycrystalline thin-film solar cells is an important strategy to test the viability

Field emission cooling of thermoelectric semiconductor PbTe M. S. Chung,1,a A. Mayer,2 B. L. Weiss due to field emission from n-type PbTe, a typical thermoelectric material. We show that, by calculating the average energies of field and replacement electrons, the energy exchange in field emission

, these devices are already produced in modules of 60x120 cm2 by two companies, namely Antec Solar in GermanyIndustrial Upscaling of CdTe/CdS Thin Film Solar Cells N. Romeoa , A. Bosioa , A. Romeob , S, ABSTRACT: CdTe/CdS thin film solar cells, since they are made with easily scalable techniques

Unusual Otto excitation dynamics and enhanced coupling of light to TE plasmons in graphene Daniel R are a unique and unusual aspect of graphene's plasmonic response that are predicted to manifest when the sign plasmons in graphene. We show that TE plasmons supported by graphene in an Otto configuration unusually

We report the influence of trap states on charge transport through films of mixed CdTe and CdSe nanocrystals (NCs) between lateral electrodes, through layered films of CdTe and CdSe NCs in a layered geometry, and through ...

been made in the quality of chlorine-doped CdTe crystals manufactured by the traveling heater method discussing the process modifications studied in the program, the steps (formation, purification, and doping. - The reaction step of Cd and Te begins when the two elements are melted in the quartz ampule at temperatures

During the last eighteen months, Abound Solar (formerly AVA Solar) has enjoyed significant success under the SAI program. During this time, a fully automated manufacturing line has been developed, fabricated and commissioned in Longmont, Colorado. The facility is fully integrated, converting glass and semiconductor materials into complete modules beneath its roof. At capacity, a glass panel will enter the factory every 10 seconds and emerge as a completed module two hours later. This facility is currently undergoing trials in preparation for large volume production of 120 x 60 cm thin film CdTe modules. Preceding the development of the large volume manufacturing capability, Abound Solar demonstrated long duration processing with excellent materials utilization for the manufacture of high efficiency 42 cm square modules. Abound Solar prototype modules have been measured with over 9% aperture area efficiency by NREL. Abound Solar demonstrated the ability to produce modules at industry leading low costs to NREL representatives. Costing models show manufacturing costs below $1/Watt and capital equipment costs below $1.50 per watt of annual manufacturing capacity. Under this SAI program, Abound Solar supported a significant research and development program at Colorado State University. The CSU team continues to make progress on device and materials analysis. Modeling for increased device performance and the effects of processing conditions on properties of CdTe PV were investigated.

During Run-Beyond-Cladding-Breach (RBCB) operation in an oxide LMR, the performance of a breached fuel element is intimately associated with the formation of fuel-sodium reaction product (FSRP), Na/sub 3/(U/sub 1-y/Pu/sub y/)O/sub 4/. In-pile experiments coupled with destructive examinations of breached fuel have consistently revealed noticeable changes in fuel structure accompanying FSRP formation at the fuel surface. Previous analyses have also indicated a significant impact of FSRP on fuel centerline temperature. Successful modeling of breached fuel thermal behavior therefore requires a reasonably accurate knowledge of the thermal properties of the FSRP, especially its thermal conductivity. But laboratory investigations have been scarce and limited to the Na/UO/sub 2/ system because of the toxicity of plutonium and hygroscopicity of the FSRP. Hence, post-irradiation observations of fuel samples remain the most amenable way of deriving the thermal conductivity of the FSRP. Such work is a spin-off of the RBCB program in the Experimental Breeder Reactor-II (EBR-II), a program jointly sponsored by the US Department of Energy and the Power Reactor and Nuclear Fuel Development Corporation of Japan.

During run-beyond-cladding-breach (RBCB) operation in an oxide liquid metal breeder, the performance of a breached fuel element is intimately associated with the formation of fuel/sodium reaction product (FSRP), Na/sub 3/(U/sub 1-y/Pu/sub y/)O/sub 4/. In-pile experiments coupled with destructive examinations of breached fuel have consistently revealed noticeable changes in fuel structure accompanying FSRP formation at the fuel surface. Previous analyses have also indicated a significant impact of FSRP on fuel centerline temperature. Successful modeling of breached fuel thermal behavior therefore requires a reasonably accurate knowledge of the thermal properties of the FSRP, especially its thermal conductivity. But laboratory investigations have been scarce and limited to the Na/UO/sub 2/ system because of the toxicity of plutonium and hygroscopicity of the FSRP. Hence, postirradiation observations of fuel samples remain the most amenable way of deriving the thermal conductivity of the FSRP. Such work is a spin-off of the RBCB program in the Experimental Breeder Reactor-II (EBR-II), a program jointly sponsored by the US Dept. of Energy and the Power Reactor and Nuclear Fuel Development Corporation of Japan.

The long-term retention of inhaled soluble forms of plutonium raises concerns as to the potential health effects in persons working in nuclear energy or the nuclear weapons program. The distributions of long-term retained inhaled plutonium-nitrate [239Pu (NO3)4] deposited in the lungs of an accidentally exposed nuclear worker (Human Case 0269) and in the lungs of experimentally exposed beagle dogs with varying initial lung depositions were determined via autoradiographs of selected histological lung, lymph node, trachea, and nasal turbinate tissue sections. These studies showed that both the human and dogs had a non-uniform distribution of plutonium throughout the lung tissue. Fibrotic scar tissue effectively encapsulated a portion of the plutonium and prevented its clearance from the body or translocation to other tissues and diminished dose to organ parenchyma. Alpha radiation activity from deposited plutonium in Human Case 0269 was observed primarily along the sub-pleural regions while no alpha activity was seen in the tracheobronchial lymph nodes of this individual. However, relatively high activity levels in the tracheobronchial lymph nodes of the beagles indicated the lymphatic system was effective in clearing deposited plutonium from the lung tissues. In both the human case and beagle dogs, the appearance of retained plutonium within the respiratory tract was inconsistent with current biokinetic models of clearance for soluble forms of plutonium. Bound plutonium can have a marked effect on the dose to the lungs and subsequent radiation exposure has the potential increase in cancer risk.

CdTe thin films grown on bi-layer graphene were demonstrated by using the close-spaced sublimation method, where CdTe was selectively grown on the graphene. The density of the CdTe domains was increased with increasing the number of the defective sites in the graphene, which was controlled by the duration of UV exposure. The CdTe growth rate on the bi-layer graphene electrodes was 400?nm/min with a bandgap energy of 1.45–1.49?eV. Scanning electron microscopy, micro-Raman spectroscopy, micro-photoluminescence, and X-ray diffraction technique were used to confirm the high quality of the CdTe thin films grown on the graphene electrodes.

The exciting results from H.E.S.S. point to a new population of gamma-ray sources at energies E > 10 TeV, paving the way for future studies and new discoveries in the multi-TeV energy range. Connected with these energies is the search for sources of PeV cosmic-rays (CRs) and the study of multi-TeV gamma-ray production in a growing number of astrophysical environments. TenTen is a proposed stereoscopic array (with a suggested site in Australia) of modest-sized (10 to 30m^2) Cherenkov imaging telescopes with a wide field of view (8 to 10deg diameter) optimised for the E~10 to 100 TeV range. TenTen will achieve an effective area of ~10 km^2 at energies above 10 TeV. We outline here the motivation for TenTen and summarise key performance parameters.

The goal of this work was to evaluate different CdTe feedstock formulations (feedstock provided by Redlen) to determine if they would significantly improve CdTe performance with ancillary benefits associated with whether changes in feedstock would affect CdTe cell processing and possibly reliability of cells. Feedstock also included attempts to intentionally dope the CdTe with pre-selected elements.

Thermoelectric Properties of Nb3SbxTe7-x Compounds Sidney Wang, G. Jeff Snyder, and Thierry Caillat antimony telluride, Nb3SbxTe7-x, was synthesized and tested for thermoelectric properties in the Thermoelectrics group at the Jet Propulsion Laboratory. The forty atoms per unit cell of Nb3Sb2Te5 and its varied

The electrooptic effect in ZnTe has recently attracted research attention, and various device structures using ZnTe have been explored. For application to practical terahertz wave detector devices based on ZnTe thin films, sapphire substrates are preferred because they enable the optical path alignment to be simplified. ZnTe/sapphire heterostructures were focused upon, and ZnTe epilayers were prepared on highly mismatched sapphire substrates by molecular beam epitaxy. Epitaxial relationships between the ZnTe thin films and the sapphire substrates with their various orientations were investigated using an X-ray diffraction pole figure method. (0001) c-plane, (1-102) r-plane, (1-100) m-plane, and (11-20) a-plane oriented sapphire substrates were used in this study. The epitaxial relationship between ZnTe and c-plane sapphire was found to be (111) ZnTe//(0001) sapphire with an in-plane orientation relationship of [?211] ZnTe//[1-100] sapphire. It was found that the (211)-plane ZnTe layer was grown on the m-plane of the sapphire substrates, and the (100)-plane ZnTe layer was grown on the r-plane sapphire. When the sapphire substrates were inclined from the c-plane towards the m-axis direction, the orientation of the ZnTe thin films was then tilted from the (111)-plane to the (211)-plane. The c-plane of the sapphire substrates governs the formation of the (111) ZnTe domain and the ZnTe epilayer orientation. These crystallographic features were also related to the atom arrangements of ZnTe and sapphire.

We develop the theory of interaction of classical plasma with Kaluza-Klein (KK) gravitons in the ADD model of TeV-scale gravity. Plasma is described within the kinetic approach as the system of charged particles and Maxwell field both confined on the brane. Interaction with multidimensional gravity living in the bulk with $n$ compact extra dimensions is introduced within the linearized theory. The KK gravitons emission rates are computed taking into account plasma collective effects through the two-point correlation functions of the fluctuations of the plasma energy-momentum tensor. Apart from known mechanisms (such as bremsstrahlung and gravi-Primakoff effect) we find essentially collective channels such as the coalescence of plasma waves into gravitons which may be manifest in turbulent plasmas. Our results indicate that commonly used rates of the KK gravitons production in stars and supernovae may be underestimated.

Observations of minute-scale flares in TeV Blazars place constraints on particle acceleration mechanisms in those objects. The implications for a variety of radiation mechanisms have been addressed in the literature; in this paper we compare four different acceleration mechanisms: diffusive shock acceleration, second-order Fermi, shear acceleration and the converter mechanism. When the acceleration timescales and radiative losses are taken into account, we can exclude shear acceleration and the neutron-based converted mechanism as possible acceleration processes in these systems. The first-order Fermi process and the converter mechanism working via SSC photons are still practically instantaneous, however, provided sufficient turbulence is generated on the timescale of seconds. We propose stochastic acceleration as a promising candidate for the energy-dependent time delays in recent gamma-ray flares of Markarian 501.

We report initial results from the design and evaluation of two pixellated PIN Cadmium Zinc Telluride detectors and an ASIC-based readout system. The prototype imaging PIN detectors consist of 4X4 1.5 mm square indium anode contacts with 0.2 mm spacing and a solid cathode plane on 10X10 mm CdZnTe substrates of thickness 2 mm and 5 mm. The detector readout system, based on low noise preamplifier ASICs, allows for parallel readout of all channels upon cathode trigger. This prototype is under development for use in future astrophysical hard X-ray imagers with 10-600 keV energy response. Measurements of the detector uniformity, spatial resolution, and spectral resolution will be discussed and compared with a similar pixellated MSM detector. Finally, a prototype design for a large imaging array is outlined.

Cadmium telluride continues to be a leading candidate for the development of cost effective photovoltaics for terrestrial applications. In the present work two individual metallic targets of Cd and Te were used for the deposition of CdTe thin films on mica substrates from room temperature to 300 °C by DC reactive magnetron sputtering method. XRD patterns of CdTe thin films deposited on mica substrates exhibit peaks at 2? = 27.7°, 46.1° and 54.6°, which corresponds to reflection on (1 1 1), (2 2 0) and (3 1 1) planes of CdTe cubic structure. The intensities of XRD patterns increases with the increase of substrate temperature upto 150 °C and then it decreases at higher substrate temperatures. The conductivity of CdTe thin films measured from four probe method increases with the increase of substrate temperature. The activation energies (?E) are found to be decrease with the increase of substrate temperature. The optical transmittance spectra of CdTe thin films deposited on mica have a clear interference pattern in the longer wavelength region. The films have good transparency (T > 85 %) exhibiting interference pattern in the spectral region between 1200 – 2500 nm. The optical band gap of CdTe thin films are found to be in the range of 1.48 – 1.57. The refractive index, n decreases with the increase of wavelength, ?. The value of n and k increases with the increase of substrate temperature.

Most work on CdTe-based solar cells has focused on devices with a superstrate structure. This focus is due to the early success of the superstrate structure in producing high-efficiency cells, problems of suitable ohmic contacts for lightly doped CdTe, and the simplicity of the structure for manufacturing. The development of the CdCl2 heat treatment boosted CdTe technology and perpetuated the use of the superstrate structure. However, despite the beneficial attributes of the superstrate structure, devices with a substrate structure are attractive both commercially and scientifically. The substrate structure eliminates the need for transparent superstrates and thus allows the use of flexible metal and possibly plastic substrates. From a scientific perspective, it allows better control in forming the junction and direct access to the junction for detailed analysis. Research on such devices has been limited. The efficiency of these devices has been limited to around 8% due to low open-circuit voltage (Voc) and fill factor. In this paper, we present our recent device development efforts at NREL on substrate-structure CdTe devices. We have found that processing parameters required to fabricate high-efficiency substrate CdTe PV devices differ from those necessary for traditional superstrate CdTe devices. We have worked on a variety of contact materials including Cu-doped ZnTe and CuxTe. We will present a comparative analysis of the performance of these contacts. In addition, we have studied the influence of fabrication parameters on junction properties. We will present an overview of our development work, which has led to CdTe devices with Voc values of more than 860 mV and NREL-confirmed efficiencies approaching 11%.

Solid State Nuclear Track Detectors are used to study a variety of atomic particles. Polycarbonate SSNTD is used to study environmental concentrations of {sup 235}U and {sup 239}Pu in human urine and feces through fission track analysis. The samples of interest are deposited upon a Lexan slide, covered with a piece of Makrofol and exposed to a neutron fluence of 1.1 X 10{sup 17}. The fissile isotopes in the sample fission and the resulting fission fragments pass through either the surface of the Lexan or the surface of the Makrofol. The positive Coulombic attraction of the ionized fission fragments causes the electrons of the polycarbonate lattice to move towards the path of these particles, resulting in the breakage of chemical bonds in the lattice. The detector is then chemically etched in 6.5 N KOH that preferentially dissolves the damaged polycarbonate left in the path of the fission fragment. The chemically etched fission tracks are permanent records of the path of the fission fragment. The etched fission tracks in Lexan are optically counted using a microscope and the fission tracks in Makrofol are counted using a Spark Chamber. The amount of fissile material in the original sample can be calculated from the number of fission tracks. This paper presents further details of procedures for etching fission tracks in Lexan and Makrofol and for operating a Spark Chamber to count etched fission tracks in Makrofol. The physics of fission track formation in dielectric detectors is also discussed, as well as the physics of the Spark Chamber.

Theoretical analyses were performed of neutron-induced reactions on {sup 235}U, {sup 238}U, {sup 237}Np, and {sup 239}Pu between 0.01 and 20 MeV in order to calculate neutron emission cross sections and spectra for ENDF/B-VI evaluations. Coupled-channel optical model potentials were obtained for each target nucleus by fitting total, elastic, and inelastic scattering cross section data, as well as low-energy average resonance data. The resulting deformed optical model potentials were used to calculate direct (n,n{prime}) cross sections and transmission coefficients for use in Hauser-Feshbach statistical theory analyses. A fission model with multiple barrier representation, width fluctuation corrections, and preequilibrium corrections were included in the analyses. Direct cross sections for higher-lying vibrational states were calculated using DWBA theory, normalized using B(E{ell}) values determined from (d,d{prime}) and Coulomb excitation data, where available, and from systematics otherwise. Initial fission barrier parameters and transition state density enhancements appropriate to the compound systems involved were obtained from previous analyses, especially fits to charged-particle fission probability data. The parameters for the fission model were adjusted for each target system to obtain optimum agreement with direct (n,f) cross section measurements, taking account of the various multichance fission channels, that is, the different compound systems involved. The results from these analyses were used to calculate most of the neutron (n,n), (n,n{prime}), and (n,xn) cross section data in the ENDF/B/VI evaluations for the above nuclei, and all of the energy-angle correlated spectra. The deformed optical model and fission model parameterizations are described. Comparisons are given between the results of these analyses and the previous ENDF/B-V evaluations as well as with the available experimental data. 14 refs., 3 figs., 1 tab.

Total-area conversion efficiency of 15%--15.8% have been achieved for thin-film CdTe and CIS solar cells. Modules with power output of 5--53 W have been demonstrated by several groups world-wide. Critical processes and reaction pathways for achieving excellent PV devices have been eluciated. Research, development and technical issues have been identified, which could result in potential improvements in device and module performance. A 1-kW thin-film CdTe array has been installed and is being tested. Multimegawatt thin-film CdTe manufacturing plants are expected to be completed in 1-2 years.

Compositionally graded p-type Bi-Sb-Te thermoelectric material was synthesized by PIES (Pulverized and Intermixed Elements Sintering) method. The materials consisted of three segmented regions of different alloy composition, i.e., y = 0.8/0.825/0.9 in (Bi{sub 2}Te{sub 3}){sub 1{minus}y} (Sb{sub 2}Te{sub 3}){sub y} system. It was found that the electrical power output of the compositionally graded material was larger than that of the best single composition material when the temperature difference was the designed value.

The chapter reviews the history, development, and present processes used to fabricate thin-film, CdTe-based photovoltaic (PV) devices. It is intended for readers who are generally familiar with the operation and material aspects of PV devices but desire a deeper understanding of the process sequences used in CdTe PV technology. The discussion identifies why certain processes may have commercial production advantages and how the various process steps can interact with each other to affect device performance and reliability. The chapter concludes with a discussion of considerations of large-area CdTe PV deployment including issues related to material availability and energy-payback time.

Copper is frequently used as a p-type dopant to improve the performance of back contacts in CdTe thin-film solar cells. In this study, surface-analysis techniques are used to probe fundamental interactions between Cu and the CdTe(111)-B surface. The results presented here were facilitated by the newly constructed surface-analysis cluster tool in the Measurements and Characterization Division at NREL; they reveal a host of fundamental phenomena that occur in the Cu/CdTe system.

Observing gamma ray bursts (GRBs) in the TeV energy range can be extremely valuable in providing insight to GRB radiation mechanisms and in constraining source distances. The Milagrito detector was an air shower array which used the water Cherenkov technique to search for TeV sources. Data from this detector was analyzed to look for a TeV component of GRBs coincident with low energy -rays detected by the BATSE instrument on the Compton Gamma Ray Observatory. A sample of 54 BATSE GRBs which were in the field of view of the Milagrito detector during its lifetime (February 1997 to May 1998) was used.

Photo-induced doping is employed into graphene based solar cell through designing of a novel type of solar cell based on graphene/CdTe Schottky heterostructure. By coating a layer of ultrathin CdSe quantum dots onto graphene/CdTe heterostructure, the performance of the graphene/CdTe solar cell is improved by about 50%. Photo-induced doping is mainly accounted for this enhancement, as evidenced by resistance, photoluminescence and quantum efficiency measurements. This work demonstrates a general and feasible way of designing novel type of solar cells based on two dimensional materials/semiconductor heterostructures.

Observing gamma ray bursts (GRBs) in the TeV energy range can be extremely valuable in providing insight to GRB radiation mechanisms and in constraining source distances. The Milagrito detector was an air shower array which used the water Cherenkov technique to search for TeV sources. Data from this detector was analyzed to look for a TeV component of GRBs coincident with low energy -rays detected by the BATSE instrument on the Compton Gamma Ray Observatory. A sample of 54 BATSE GRBs which were in the field of view of the Milagrito detector during its lifetime (February 1997 to May 1998) was used.

We used X-ray/neutron diffraction to determine the low temperature (LT) structure of IrTe2. A structural modulation was observed with a wavevector of k =(1/5, 0, 1/5) below Ts285 K, accompanied by a structural transition from a trigonal to a triclinic lattice. We also performed the first principles calculations for high temperature (HT) and LT structures, which elucidate the nature of the phase transition and the LT structure. A local bonding instability associated with the Te 5p states is likely the origin of the structural phase transition in IrTe2.

It is shown that the absorption of photons at energies > 1 TeV (much higher than the mass of the Higgs boson ~ 100 GeV) is a multi-channel one as opposed to the purely electron pair like absorption at lower energies. The observation on muons and gamma rays from Cygnus X-3 point source at these energies (1 TeV to 10 TeV) is quantitatively accounted for. The expected multi-channel cross-sections of photons in air as a function of energy is given both for Coulomb dissociation and nuclear absorption upto limiting energies of 10^9 GeV.

Subsolidus phase relationships in the 2(ZnTe){sub x}(CuInTe{sub 2}){sub 1-x} system were investigated by TEM experiments combined with EDX analysis. The samples were prepared by the solid-state reaction of the elements during long annealing times, followed by either quenching in ice-cold water, or by controlled cooling at different rates. Using the chemical compositions of single and coexisting phases at various temperatures, the boundaries of the two-phase region have been determined. At room temperature, the two-phase region extends from x=0.10 to 0.31. For x<0.10 only mixed crystals with tetragonal structure exist. Between x=0.31 and 1 alloys with the cubic structure are stable. The morphology of the tetragonal domains and their orientation relationship to the cubic matrix were determined by SAD, TEM and HRTEM experiments. The tetragonal phase embedded within the cubic matrix has a flat ellipsoidal shape, whose short axis coincides with the tetragonal c-axis. The three topotaxial orientation relationships between the tetragonal domains and the surrounding cubic matrix were found to be: [001]{sub tetr.}-bar [100]{sub cub.}, [001]{sub tetr.}-bar [010]{sub cub.} and [001]{sub tetr.}-bar [001]{sub cub.}. There is an indication that the nucleation starts from small regions displaying cation ordering according to the CuPt-type structure. Reaching the two-phase equilibrium, the tetragonal domains as well as the surrounding cubic phase are free of this cation ordering.

Although our goal is to isolate anaerobic EDTA degraders, we initiated the experiments to include nitrilotriacetate (NTA), which is a structure homologue of EDTA. All the aerobic EDTA degraders can degrade NTA, but the isolated NTA degraders cannot degrade EDTA. Since NTA is a simpler structure homologue, it is likely that EDTA-degrading ability is evolved from NTA degradation. This hypothesis is further supported from our characterization of EDTA and NTA-degrading enzymes and genes (J. Bact. 179:1112-1116; and Appl. Environ. Microbiol. 67:688-695). The EDTA monooxygenase and NTA monooxygenase are highly homologous. EDTA monooxygenase can use both EDTA and NTA as substrates, but NTA monooxygenase can only use NTA as a substrate. Thus, we put our effort to isolate both NTA and EDTA degraders. In case, an anaerobic EDTA degrader is not immediately enriched, we will try to evolve the NTA degraders to use EDTA. Both aerobic and anaerobic enrichment cultures were set.

The objective of this report is to isolate anaerobic EDTA-degrading bacteria. Although our goal is to isolate anaerobic EDTA degraders, we initiated the experiments to include nitrilotriacetate (NTA), which is a structure homologue of EDTA. All the aerobic EDTA degraders can degrade NTA, but the isolated NTA degraders cannot degrade EDTA. Since NTA is a simpler structure homologue, it is likely that EDTA-degrading ability is evolved from NTA degradation. This hypothesis is further supported from our characterization of EDTA and NTA-degrading enzymes and genes (J. Bact. 179:1112-1116; and Appl. Environ. Microbiol. 67:688-695). The EDTA monooxygenase and NTA monooxygenase are highly homologous. EDTA monooxygenase can use both EDTA and NTA as substrates, but NTA monooxygenase can only use NTA as a substrate. Thus, we put our effort to isolate both NTA and EDTA degraders. In case, an anaerobic EDTA degrader is not immediately enriched, we will try to evolve the NTA degraders to use EDTA. Both aerobic and anaerobic enrichment cultures were set.

We show by density functional theory calculations that asymmetric hetero-stacking of Bi{sub 2}Te{sub 3}/Sb{sub 2}Te{sub 3} films can modulate the topological surface states. Due to the structure inversion asymmetry, an intrinsic Rashba-like splitting of the conical surface bands is aroused. While such splitting in homogeneous Bi{sub 2}Te{sub 3}-class topological insulators can be realized in films with more than three quintuple layers under external electric fields, the hetero-stacking breaks the limit of thickness for preserving the topological nature into the thinnest two quintuple layers. These results indicate that the hetero-stacking can serve as an efficient strategy for spin-resolved band engineering of topological insulators.

Nanocrystalline Co defused CdTe thin films were prepared using electron beam evaporation technique by depositing CdTe/Co/CdTe stacked layers with different Co thickness onto glass substrate at 373 K followed by annealing at 573K for 2 hrs. Structural, morphological and magnetic properties of of all the Co defused CdTe thin films has been investigated. XRD pattern of all the films exhibited zinc blende structure with <111> preferential orientation without changing the crystal structure of the films. The grain size of the films increased from 31.5 nm to 48.1 nm with the increase of Co layer thickness from 25nm to 100nm. The morphological studies showed that uniform texture of the films and the presence of Co was confirmed by EDAX. Room temperature magnetization curves indicated an improved ferromagnetic behavior in the films with increase of the Co thickness.

Lead telluride (PbTe) is an established thermoelectric material which can be alloyed with sulphur and selenium to further enhance the thermoelectric properties. Here, a first principles study of ternary alloys PbS{sub x}Te{sub (1?x)} and PbSe{sub x}Te{sub (1?x)} (0?x?1) based on the Virtual Crystal Approximation (VCA) is presented for different ratios of the isoelectronic atoms in each series. Equilibrium lattice parameters and elastic constants have been calculated and compared with the reported data. Anisotropy parameter calculated from the stiffness constants showed a slight improvement in anisotropy of elastic properties of the alloys over undoped PbTe. Furthermore, the alloys satisfied the predicted stability criteria from the elastic constants, showing stable structures, which agreed with the previously reported experimental results.

We propose that TeV $\\gamma$-ray emission from blazars is produced by collisions near the line of sight of high energy jet protons with gas targets (``clouds'') from the broad emission-line region (BLR). Intense TeV $\\gamma$-ray flares (GRFs) are produced when BLR clouds cross the line of sight close to the black hole. The model reproduces the observed properties of the recently reported very short and intense TeV GRFs from the blazar Markarian 421. Hadronic production of TeV GRF from blazars implies that it is accompanied by a simultaneous emission of high energy neutrinos, and of electrons and positrons with similar intensities, light curves and energy spectra. Cooling of these electrons and positrons by emission of synchrotron radiation and inverse Compton scattering produces delayed optical, X-ray and $\\gamma$-ray flares.

A neutron or proton excess in nuclei leads to an isovector-vector mean-field which, through its coupling to the quarks in a bound nucleon, implies a shift in the quark distributions with respect to the Bjorken scaling variable. We show that this result leads to an additional correction to the NuTeV measurement of sin^2Theta_W. The sign of this correction is largely model independent and acts to reduce the NuTeV result. Explicit calculation within a covariant and confining Nambu Jona-Lasinio model predicts that this vector field correction accounts for approximately two-thirds of the NuTeV anomaly. We are therefore led to offer a new interpretation of the NuTeV measurement, namely, that it is further evidence for the medium modification of the bound nucleon wavefunction.

transients, such as gamma-ray bursts, and all sky surveys are diÆcult. A new type of TeV -ray observatoryMilagro: A TeV Gamma-Ray Monitor of the Northern Hemisphere Sky B.L. Dingus 1 , R. Atkins 1 , W type of very high energy (> a few 100 GeV) gamma-ray observatory, Milagro, has been built with a large

Highlights: ? PbTe nanoneedles were prepared at low temperature without any surfactant or template. ? The synthetic method is very simple, economical and environment benign. ? PbTe nanoneedles exhibit low resistivity, which improves thermoelectric performance. ? PbTe nanoneedles show large blue-shift due to quantum confinement effect. - Abstract: The face-centered cubic PbTe micro-needles were synthesized by a simple aqueous chemical reaction between lead acetate and tellurium in NaOH solution in the presence of Na{sub 2}HPO{sub 4} as reducing reagent at low temperature under atmospheric pressure without any additional surfactants or templates. Micro structural analyses show that these micro-needles are in the range of 90–130 nm in diameter with length ?2 ?m. Electrical resistivity of prepared PbTe micro-needles was found to be 14–33 Ohm-cm. The optical absorption spectrum of PbTe micro-needles shows large blue-shift (?1.26 eV) with respect to those of the bulk counterpart (0.32 eV) due to quantum confinement of charge carriers, which is consistent with the blue shift of the band emission peak in the photoluminescence spectrum.

We report the detection of a new TeV gamma-ray source, VER J0521+211, based on observations made with the VERITAS imaging atmospheric Cherenkov Telescope Array. These observations were motivated by the discovery of a cluster of >30 GeV photons in the first year of Fermi Large Area Telescope observations. VER J0521+211 is relatively bright at TeV energies, with a mean photon flux of (1.93 ± 0.13{sub stat} ± 0.78{sub sys}) × 10{sup –11} cm{sup –2} s{sup –1} above 0.2 TeV during the period of the VERITAS observations. The source is strongly variable on a daily timescale across all wavebands, from optical to TeV, with a peak flux corresponding to ?0.3 times the steady Crab Nebula flux at TeV energies. Follow-up observations in the optical and X-ray bands classify the newly discovered TeV source as a BL Lac-type blazar with uncertain redshift, although recent measurements suggest z = 0.108. VER J0521+211 exhibits all the defining properties of blazars in radio, optical, X-ray, and gamma-ray wavelengths.

We report on TeV {gamma}-ray observations of the blazar Mrk 421 (redshift of 0.031) with the VERITAS observatory and the Whipple 10 m Cherenkov telescope. The excellent sensitivity of VERITAS allowed us to sample the TeV {gamma}-ray fluxes and energy spectra with unprecedented accuracy where Mrk 421 was detected in each of the pointings. A total of 47.3 hr of VERITAS and 96 hr of Whipple 10 m data were acquired between 2006 January and 2008 June. We present the results of a study of the TeV {gamma}-ray energy spectra as a function of time and for different flux levels. On 2008 May 2 and 3, bright TeV {gamma}-ray flares were detected with fluxes reaching the level of 10 Crab. The TeV {gamma}-ray data were complemented with radio, optical, and X-ray observations, with flux variability found in all bands except for the radio wave band. The combination of the Rossi X-ray Timing Explorer and Swift X-ray data reveal spectral hardening with increasing flux levels, often correlated with an increase of the source activity in TeV {gamma}-rays. Contemporaneous spectral energy distributions were generated for 18 nights, each of which are reasonably described by a one-zone synchrotron self-Compton model.

Recently, CdTe photovoltaic (PV) devices fabricated in the nonstandard substrate configuration have attracted increasing interest because of their potential compatibility with flexible substrates such as metal foils and polymer films. This compatibility could lead to the suitability of CdTe for roll-to-roll processing and building-integrated PV. Currently, however, the efficiencies of substrate CdTe devices reported in the literature are significantly lower ({approx}6%-8%) than those of high-performance superstrate devices ({approx}17%) because of significantly lower open-circuit voltage (Voc) and fill factor (FF). In our recent device development efforts, we have found that processing parameters required to fabricate high-efficiency substrate CdTe PV devices differ from those necessary for traditional superstrate CdTe devices. Here, we investigate how oxygen incorporation in the CdTe deposition, CdCl2 heat treatment, CdS deposition, and post-deposition heat treatment affect device characteristics through their effects on the junction. By adjusting whether oxygen is incorporated during these processing steps, we have achieved Voc values greater than 860 mV and efficiencies greater than 10%.

A method of making a low-resistance electrical contact between a p-CdTe layer and outer contact layers by ion beam processing comprising: a) placing a CdS/CdTe device into a chamber and evacuating the chamber; b) orienting the p-CdTe side of the CdS/CdTe layer so that it faces apparatus capable of generating Ar atoms and ions of preferred energy and directionality; c) introducing Ar and igniting the area of apparatus capable of generating Ar atoms and ions of preferred energy and directionality in a manner so that during ion exposure, the source-to-substrate distance is maintained such that it is less than the mean-free path or diffusion length of the Ar atoms and ions at the vacuum pressure; d) allowing exposure of the p-CdTe side of the device to said ion beam for a period less than about 5 minutes; and e) imparting movement to the substrate to control the real uniformity of the ion-beam exposure on the p-CdTe side of the device.

We study the prospects for long-lived charged particle (LLCP) searches at current and future LHC runs and at a 100 TeV pp collider, using Drell-Yan slepton pair production as an example. Because momentum measurements become more challenging for very energetic particles, we carefully treat the expected momentum resolution. At the same time, a novel feature of 100 TeV collisions is the significant energy loss of energetic muons in detectors. We use this to help discriminate between muons and LLCPs. We find that the 14 TeV LHC with an integrated luminosity of 3 ab$^{-1}$ can probe LLCP slepton masses up to 1.2 TeV, and a 100 TeV pp collider with 3 ab$^{-1}$ can probe LLCP slepton masses up to 4 TeV, using time-of-flight measurements. These searches will have striking implications for dark matter, with the LHC definitively testing the possibility of slepton-neutralino co-annihilating WIMP dark matter, and with the LHC and future hadron colliders having a strong potential for discovering LLCPs in models with super...

We study the prospects for long-lived charged particle (LLCP) searches at current and future LHC runs and at a 100 TeV pp collider, using Drell-Yan slepton pair production as an example. Because momentum measurements become more challenging for very energetic particles, we carefully treat the expected momentum resolution. At the same time, a novel feature of 100 TeV collisions is the significant energy loss of energetic muons in detectors. We use this to help discriminate between muons and LLCPs. We find that the 14 TeV LHC with an integrated luminosity of 3 ab$^{-1}$ can probe LLCP slepton masses up to 1.2 TeV, and a 100 TeV pp collider with 3 ab$^{-1}$ can probe LLCP slepton masses up to 4 TeV, using time-of-flight measurements. These searches will have striking implications for dark matter, with the LHC definitively testing the possibility of slepton-neutralino co-annihilating WIMP dark matter, and with the LHC and future hadron colliders having a strong potential for discovering LLCPs in models with superWIMP dark matter.

CuIn{sub 1?x}Cd{sub x}Te{sub 2} materials (x?=?0, 0.02, 0.05, and 0.1) are prepared using melting-annealing method and the highly densified bulk samples are obtained through Spark Plasma Sintering. The X-ray diffraction data confirm that nearly pure chalcopyrite structures are obtained in all the samples. Due to the substitution of Cd at In sites, the carrier concentration is greatly increased, leading to much enhanced electrical conductivity and power factor. The single parabolic band model is used to describe the electrical transport properties of CuInTe{sub 2} and the low temperature Hall mobility is also modeled. By combing theoretical model and experiment data, the optimum carrier concentration in CuInTe{sub 2} is proposed to explain the greatly enhanced power factors in the Cd doped CuInTe{sub 2}. In addition, the thermal conductivity is reduced by extra phonon scattering due to the atomic mass and radius fluctuations between Cd and In atoms. The maximum zTs are observed in CuIn{sub 0.98}Cd{sub 0.02}Te{sub 2} and CuIn{sub 0.9}Cd{sub 0.1}Te{sub 2} samples, which are improved by over 100% at room temperature and around 20% at 600?K.

Efforts are underway to improve the design and sensitivity of gravitational waves detectors, with the hope that the next generation of these detectors will observe a gravitational wave signal. Such a signal will not only provide information on dynamics in the strong gravity regime that characterizes potential sources of gravitational waves, but will also serve as a decisive test for alternative theories of gravitation that are consistent with all other current experimental observations. We study the linearized theory of the tensor-vector-scalar theory of gravity (TeVeS) with generalized vector action, an alternative theory of gravitation designed to explain the apparent deficit of visible matter in galaxies and clusters of galaxies without postulating yet undetected dark matter. We find the polarization states and propagation speeds for gravitational waves in vacuum, and show that in addition to the usual transverse-traceless propagation modes, there are two more transverse modes and two trace modes. Additionally, the propagation speeds are different from c.

We build a gauge model based on the SU(3)_c x SU(4)_L x U(1)_X symmetry where the scalar spectrum needed to generate gauge boson and fermion masses has a smaller scalar content than usually assumed in literature. We compute the running of its abelian gauge coupling and show that a Landau pole shows up at the TeV scale, a fact that we use to consistently implement those fermion masses that are not generated by Yukawa interactions, including neutrino masses. This is appropriately achieved by non renormalizable effective operators, suppressed by the Landau pole scale. Also, SU(3)_c x SU(3)_L x U(1)_N models embedded in this gauge structure are bound to be strongly coupled at this same energy scale, contrary to what is generally believed, and neutrino mass generation is rather explained through the same effective operators used in the larger gauge group. Besides, their nice features, as the existence of cold dark matter candidates and the ability to reproduce the observed standard model Higgs-like phenomenology, are automatically inherited by our model. Finally, our results imply that this model is constrained to be observed or discarded soon, since it must be realized at the currently probed energy scale in LHC.

A 3 cm{sup 3} multichannel gamma spectrometer for DOE applications is under development by Digirad Corporation. The device is based on a position sensitive detector packaged in a compact multi-chip module (MCM) with integrated readout circuitry. The modular, multichannel design will enable identification and quantitative analysis of radionuclides in extended sources, or sources containing low levels of activity. The MCM approach has the advantages that the modules are designed for imaging applications, and the sensitivity can be arbitrarily increased by increasing the number of pixels, i.e. adding modules to the instrument. For a high sensitivity probe, the outputs for each pixel can be corrected for gain and offset variations, and summed digitally. Single pixel results obtained with discrete low noise readout indicate energy resolution of 3 keV can be approached with currently available CdZnTe. The energy resolution demonstrated to date with MCMs for 511 keV gamma rays is 10 keV.

We describe initial results of our program to develop and test Cd-Zn-Te (CZT) detectors with a pixellated array readout. Our primary interest is in the development of relatively thick CZT detectors for use in astrophysical coded aperture telescopes with response extending over the energy range $\\sim 10-600$ keV. The coded aperture imaging configuration requires only relatively large area pixels (1-3 mm), whereas the desired high energy response requires detector thicknesses of at least 3-5 mm. We have developed a prototype detector employing a 10 x 10 x 5 mm CZT substrate and 4 x 4 pixel (1.5 mm each) readout with gold metal contacts for the pixels and continuous gold contact for the bias on the opposite detector face. This MSM contact configuration was fabricated by RMD and tested at Harvard for uniformity, efficiency and spatial as well as spectral resolution. We have developed an ASIC readout (IDE-VA-1) and analysis system and report results, including $\\sim 4$% (FWHM) energy resolution at 60 keV. A prototype design for a full imaging detector array is discussed.

High quality Bi2Te3 and Sb2Te3 topological insulators films were epitaxially grown on GaAs (111) substrate using solid source molecular beam epitaxy. Their growth and behavior on both vicinal and non-vicinal GaAs (111) substrates were investigated by reflection high-energy electron diffraction, atomic force microscopy, x-ray diffraction, and high resolution transmission electron microscopy. It is found that non-vicinal GaAs (111) substrate is better than a vicinal substrate to provide high quality Bi2Te3 and Sb2Te3 films. Hall and magnetoresistance measurements indicate that p type Sb2Te3 and n type Bi2Te3 topological insulator films can be directly grown on a GaAs (111) substrate, which may pave a way to fabricate topological insulator p-n junction on the same substrate, compatible with the fabrication process of present semiconductor optoelectronic devices.

The electronic properties and Seebeck coefficients of Ce{sub 3}Te{sub 4} and La{sub 3}Te{sub 4} are computed using Density Functional Theory with on-site Coulomb interaction correction. We found that the Seebeck coefficients of Ce{sub 3}Te{sub 4} and La{sub 3}Te{sub 4} are almost equal at temperatures larger than the Curie temperature of Ce{sub 3}Te{sub 4}, and in good agreement with the measurements reported by May et al. [Phys. Rev. B 86, 035135 (2012)]. At temperatures below the Curie temperature, the Seebeck coefficient of Ce{sub 3}Te{sub 4} increases due to the ferromagnetic ordering, which leads the f-electron of Ce to contribute to the Seebeck coefficient in the relevant range of electron concentration.

The University of Wisconsin Department of Engineering Professional Development (EPD) has completed the sponsored project entitled, Development of a Total Energy, Environment and Asset Management (TE2AM™) Curriculum. The project involved the development of a structured professional development program to improve the knowledge, skills, capabilities, and competencies of engineers and operators of commercial buildings. TE2AM™ advances a radically different approach to commercial building design, operation, maintenance, and end-­?of-­?life disposition. By employing asset management principles to the lifecycle of a commercial building, owners and occupants will realize improved building performance, reduced energy consumption and positive environmental impacts. Through our commercialization plan, we intend to offer TE2AM™ courses and certificates to the professional community and continuously improve TE2AM™ course materials. The TE2AM™ project supports the DOE Strategic Theme 1 -­? Energy Security; and will further advance the DOE Strategic Goal 1.4 Energy Productivity. Through participation in the TE2AM™ curriculum, engineers and operators of commercial buildings will be eligible for a professional certificate; denoting the completion of a prescribed series of learning activities. The project involved a comprehensive, rigorous approach to curriculum development, and accomplished the following goals: 1. Identify, analyze and prioritize key learning needs of engineers, architects and technical professionals as operators of commercial buildings. 2. Design and develop TE2AM™ curricula and instructional strategies to meet learning needs of the target learning community. 3. Establish partnerships with the sponsor and key stakeholders to enhance the development and delivery of learning programs. 4. Successfully commercialize and sustain the training and certificate programs for a substantial time following the term of the award. The project team was successful in achieving the goals and deliverables set forth in the original proposal. Though attempts were made to adhere to the original project timeline, the team requested, and was granted a 6-­?month project extension, during which time the project was completed.

In view of the annnouncement that in 2012 the LHC will run at 8 TeV, we study the possibility of detecting signals of alternative mechanisms of ElectroWeak Symmetry Breaking, described phenomenologically by unitarized models, at energies lower than 14 TeV. A complete calculation with six fermions in the final state is performed using the PHANTOM event generator. Our results indicate that at 8 TeV some of the scenarios with TeV scale resonances are likely to be identified while models with no resonances or with very heavy ones will be inaccessible, unless the available luminosity will be much higher than expected.

In view of the annnouncement that in 2012 the LHC will run at 8 TeV, we study the possibility of detecting signals of alternative mechanisms of ElectroWeak Symmetry Breaking, described phenomenologically by unitarized models, at energies lower than 14 TeV. A complete calculation with six fermions in the final state is performed using the PHANTOM event generator. Our results indicate that at 8 TeV some of the scenarios with TeV scale resonances are likely to be identified while models with no resonances or with very heavy ones will be inaccessible, unless the available luminosity will be much higher than expected.

Min-K 1400TE insulation material was characterized at Oak Ridge National Laboratory for use in structural applications under gradient temperature conditions. Initial compression testing was performed at room temperature at various loading rates ranging between 5 and 500 psi/hour (?35 and 3500 kPa/hour) to determine the effect of sample size and test specimen geometry on the compressive strength of Min-K. To determine the loading rates that would be used for stress relaxation testing, compression tests were next carried out at various levels followed by stress relaxation under constant strain at temperatures of 650, 850, and 900oC. Additional high temperature compression testing was performed with samples loaded at a rate of 53 psi/hour (365 kPa/hour) in three load steps of 50, 100 and 200 psi (345, 690, and 1380 kPa) with quick unload/load cycles between steps and followed by a hold period in load control (3 to 100 hours) to allow for sample creep. Testing was carried out at 190, 382, 813, and 850oC. Isothermal stress relaxation testing was performed at temperatures of 190, 382, 813, and 850oC and initial loads of 100 and 200 psi (690 and 1380 kPa). Gradient stress relaxation testing was intended to be performed at temperatures of 850/450oC and 450/190oC with initial loads of 100 or 200 psi (690 and 1380 kPa) performed under constant strain utilizing a twelve-step loading scheme with loading every half hour at a rate of 5.56% strain/hour.

In a model of TeV right-handed (RH) neutrino by Krauss, Nasri, and Trodden, the sub-eV scale neutrino masses are generated via a 3-loop diagram with the vanishing see-saw mass forbidden by a discrete symmetry, and the TeV mass RH neutrino is simultaneously a novel candidate for the cold dark matter. However, we show that with a single RH neutrino it is not possible to generate two mass-square differences as required by the oscillation data. We extend the model by introducing one more TeV RH neutrino and show that it is possible to satisfy the oscillation pattern within the modified model. After studying in detail the constraints coming from the dark matter, lepton flavor violation and the muon anomalous magnetic moment, and the neutrinoless double beta decay, we explore the parameter space and derive predictions of the model. Finally, we study the production and decay signatures of the TeV RH neutrinos at TeV $e^+ e^-/\\mu^+ \\mu^-$ colliders.

SnTe is a conventional thermoelectric material and has been newly found to be a topological crystalline insulator. In this work, back-gate SnTe field-effect transistors have been fabricated and fully characterized. The devices exhibit n-type transistor behaviors with excellent current-voltage characteristics and large on/off ratio (>10{sup 6}). The device threshold voltage, conductance, mobility, and subthreshold swing have been studied and compared at different temperatures. It is found that the subthreshold swings as a function of temperature have an apparent response to the SnTe phase transition between cubic and rhombohedral structures at 110?K. The abnormal and rapid increase in subthreshold swing around the phase transition temperature may be due to the soft phonon/structure change which causes the large increase in SnTe dielectric constant. Such an interesting and remarkable electrical response to phase transition at different temperatures makes the small SnTe transistor attractive for various electronic devices.

The diffuse gamma radiation arising from the interaction of cosmic ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of the cosmic rays. Milagro is a water Cherenkov detector that continuously views the entire overhead sky. The large field-of-view combined with the long observation time makes Milagro the most sensitive instrument available for the study of large, low surface brightness sources such as the diffuse gamma radiation arising from interactions of cosmic radiation with interstellar matter. In this paper we present spatial and flux measurements of TeV gamma-ray emission from the Cygnus Region. The TeV image shows at least one new source MGRO J2019+37 as well as correlations with the matter density in the region as would be expected from cosmic-ray proton interactions. However, the TeV gamma-ray flux as measured at {approx}12 TeV from the Cygnus region (after excluding MGRO J2019+37) exceeds that predicted from a conventional model of cosmic ray production and propagation. This observation indicates the existence of either hard-spectrum cosmic-ray sources and/or other sources of TeV gamma rays in the region.

The diffuse gamma radiation arising from the interaction of cosmic ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of the cosmic rays. Milagro is a water Cherenkov detector that continuously views the entire overhead sky. The large field-of-view combined with the long observation time makes Milagro the most sensitive instrument available for the study of large, low surface brightness sources such as the diffuse gamma radiation arising from interactions of cosmic radiation with interstellar matter. In this paper we present spatial and flux measurements of TeV gamma-ray emission from the Cygnus Region. The TeV image shows at least one new source MGRO J2019+37 as well as correlations with the matter density in the region as would be expected from cosmic-ray proton interactions. However, the TeV gamma-ray flux as measured at ~12 TeV from the Cygnus region (after excluding MGRO J2019+37) exceeds that predicted from a conventional model of cosmic ray production and propagation. This observation indicates the existence of either hard-spectrum cosmic-ray sources and/or other sources of TeV gamma rays in the region.

The total cross sections for the 120Te(p,gamma)121I and 120Te(p,n)120I reactions have been measured by the activation method in the effective center-of-mass energies between 2.47 MeV and 7.93 MeV. The targets were prepared by evaporation of 99.4 % isotopically enriched 120Te on Aluminum and Carbon backing foils, and bombarded with proton beams provided by the FN tandem accelerator at the University of Notre Dame. The cross sections and $S$ factors were deduced from the observed gamma ray activity, which was detected off-line by two Clover HPGe detectors mounted in close geometry. The results are presented and compared with the predictions of statistical model calculations using the codes NON-SMOKER and TALYS.

Results are reported from a search for the effects of contact interactions using events with a high-mass, oppositely charged muon pair. The events are collected in proton-proton collisions at s?=7 TeV using the Compact Muon Solenoid detector at the Large Hadron Collider. The data sample corresponds to an integrated luminosity of 5.3 fb?¹. The observed dimuon mass spectrum is consistent with that expected from the standard model. The data are interpreted in the context of a quark- and muon-compositeness model with a left-handed isoscalar current and an energy scale parameter ?. The 95% confidence level lower limit on ? ismore »9.5 TeV under the assumption of destructive interference between the standard model and contact-interaction amplitudes. For constructive interference, the limit is 13.1 TeV. These limits are comparable to the most stringent ones reported to date.« less

Three-dimensional topological insulators are a new state of quantum matter with a bulk gap and odd number of relativistic Dirac fermions on the surface. By investigating the surface state of Bi{sub 2}Te{sub 3} with angle-resolved photoemission spectroscopy, we demonstrate that the surface state consists of a single nondegenerate Dirac cone. Furthermore, with appropriate hole doping, the Fermi level can be tuned to intersect only the surface states, indicating a full energy gap for the bulk states. Our results establish that Bi{sub 2}Te{sub 3} is a simple model system for the three-dimensional topological insulator with a single Dirac cone on the surface. The large bulk gap of Bi{sub 2}Te{sub 3} also points to promising potential for high-temperature spintronics applications.

Bi{sub 2}Te{sub 3} is a topological insulator with time reversal symmetry possessing a single Dirac cone at a given surface. The surface states of topological insulators play a critical role in exotic physical phenomena and their applications. We investigate the surface states of thin films of Bi{sub 2}Te{sub 3}(111) using density-functional theory including spin-orbit coupling. Considering one to six quintuple layers (QLs) of Bi{sub 2}Te{sub 3} films, we identify the surface states from calculated band structures using the decay length of the surface states and electron density plots. We show that the films of 1 and 2 QLs are too thin to hold the surface states protected topologically, and that for thicker films bands identified as surface states at {Gamma}-bar lose their surface-state features away from {Gamma}-bar. This method can be applied to other topological insulators.

Lead telluride and its alloys are well known for their thermoelectric applications. Here, a systematic study of PbTe{sub 1-y}Se{sub y} alloys doped with indium has been done. The powder X-Ray diffraction combined with Rietveld analysis confirmed the polycrystalline single phase nature of the samples, while microstructural analysis with scanning electron microscope results showed densification of samples and presence of micrometer sized particles. The temperature dependent transport properties showed that in these alloys, indium neither pinned the Fermi level as it does in PbTe, nor acted as a resonant dopant as in SnTe. At high temperatures, bipolar effect was observed which restricted the zT to 0.66 at 800?K for the sample with 30% Se content.

The observations of high energy $\\gamma$-ray emission from the Galactic center (GC) by HESS, and recently by Fermi, suggest the cosmic ray acceleration in the GC and possibly around the supermassive black hole. In this work we propose a lepton-hadron hybrid model to explain simultaneously the GeV-TeV $\\gamma$-ray emission. Both electrons and hadronic cosmic rays were accelerated during the past activity of the GC. Then these particles would diffuse outwards and interact with the interstellar gas and background radiation field. The collisions between hadronic cosmic rays with gas is responsible to the TeV $\\gamma$-ray emission detected by HESS. With fast cooling in the strong radiation field, the electrons would cool down and radiate GeV photons through inverse Compton scattering off the soft background photons. This scenario provides a natural explanation of the observed GeV-TeV spectral shape of $\\gamma$-rays.

We employed measurement of the Pockels electro-optic effect to study the electric field and space charge dynamics in semi-insulating CdTe doped with indium. We performed measurements of time and temperature dependence of the electric field. The polarization due to space charge build-up decreases with increasing temperature. Increase of temperature, therefore, leads to de-polarization in CdTe:In detectors which are opposite to the CdTe:Cl samples studied to date. We have shown that the thermally activated depolarization cannot be explained by the conventional model used for the description of space charge formation so far and an alternative model involving a recombination level was suggested and successfully used.

Results are reported from a search for the effects of contact interactions using events with a high-mass, oppositely charged muon pair. The events are collected in proton-proton collisions at s?=7 TeV using the Compact Muon Solenoid detector at the Large Hadron Collider. The data sample corresponds to an integrated luminosity of 5.3 fb?¹. The observed dimuon mass spectrum is consistent with that expected from the standard model. The data are interpreted in the context of a quark- and muon-compositeness model with a left-handed isoscalar current and an energy scale parameter ?. The 95% confidence level lower limit on ? is 9.5 TeV under the assumption of destructive interference between the standard model and contact-interaction amplitudes. For constructive interference, the limit is 13.1 TeV. These limits are comparable to the most stringent ones reported to date.

Pair correlations in the ground state of {sup 130}Te have been investigated using pair-transfer experiments to explore the validity of approximations in calculating the matrix element for neutrinoless double-{beta} decay. This nucleus is a candidate for the observation of such decay, and a good understanding of its structure is crucial for eventual calculations of the neutrino mass, should such a decay indeed be observed. For proton-pair adding, strong transitions to excited 0{sup +} states had been observed in the Te isotopes by Alford et al. [Nucl. Phys. A 323, 339 (1979)], indicating a breaking of the BCS approximation for protons in the ground state. We measured the neutron-pair removing (p,t) reaction on {sup 130}Te and found no indication of a corresponding splitting of the BCS nature of the ground state for neutrons.

Pair correlations in the ground state of {sup 130}Te have been investigated using pair-transfer experiments to explore the validity of approximations in calculating the matrix element for neutrinoless double-{beta} decay. This nucleus is a candidate for the observation of such decay, and a good understanding of its structure is crucial for eventual calculations of the neutrino mass, should such a decay indeed be observed. For proton-pair adding, strong transitions to excited 0{sup +} states had been observed in the Te isotopes by Alford et al. [Nucl. Phys. A 323, 339 (1979)], indicating a breaking of the BCS approximation for protons in the ground state. We measured the neutron-pair removing (p,t) reaction on {sup 130}Te and found no indication of a corresponding splitting of the BCS nature of the ground state for neutrons.

In light of the recent discovery of the importance of the isovector EMC effect for the interpretation of the NuTeV determination of sin2 #18;W, it seems timely to reassess the central value and the errors on this fundamental Standard Model parameter derived from the NuTeV data. We also include earlier work on charge symmetry violation and the recent limits on a possible asymmetry between s and ¯s quarks. With these corrections we find a revised NuTeV result of sin2 #18;W = 0.2232 ± 0.0013(stat) ± 0.0024(syst), which is in excellent agreement with the running of sin2 #18;W predicted by the Standard Model.

Here, we report thermoelectric study of crossroads material MnTe via iso-electronic doping S on the Te-site. MnTe{sub 1-x}S{sub x} samples with nominal S content of x?=?0.00, 0.05, and 0.10 were prepared using a melt-quench method followed by pulverization and spark plasma sintering. The X-ray powder diffraction, scanning electron microscopy, and ZAF-corrected compositional analysis confirmed that S uniformly substitutes Te up to slightly over 2%. A higher content of S in the starting materials led to the formation of secondary phases. The thermoelectric properties of MnTe{sub 1-x}S{sub x} samples were characterized by means of Seebeck coefficient, electrical conductivity, and thermal conductivity measurements from 300?K to 773?K. Furthermore, Hall coefficient measurements and a single parabolic band model were used to help gain insights on the effects of S-doping on the scattering mechanism and the carrier effective mass. As expected, S doping not only introduced hole charge carriers but also created short-range defects that effectively scatter heat-carrying phonons at elevated temperatures. On the other hand, we found that S doping degraded the effective mass. As a result, the ZT of MnTe{sub 0.9}S{sub 0.1} was substantially enhanced over the pristine sample near 400?K, while the improvement of ZT became marginal at elevated temperatures. A ZT???0.65 at 773?K was obtained in all three samples.

The WZ associated diboson production is studied by measuring both inclusive cross section and, for the first time, the ratio between the $W^-Z$ and the $W^+Z$ cross sections. The measurements are performed using data samples of proton-proton collisions collected during the years 2011 and 2012, at 7 and 8 TeV of centre-of-mass energies, respectively, by the CMS experiment at the LHC, updating the 7 TeV cross section measurement available in CMS, and presenting the new cross section measurement in CMS at 8 TeV. The data sample used for the 7 TeV measurements correspond to an integrated luminosity of 4.9 $fb^{-1}$, whence the data for the 8 TeV correspond to $\\mathcal{L}_{int}=19.6~fb^{-1}$. The obtained results are found compatible with the Standard Model predictions.

electromagnetic air showers in the Milagro gamma-ray observatory, based on the ability to detect the energetic the late 1980s that the first convincing detection of a source of TeV gamma rays was made with a ground by the Whipple experiment to detect TeV gamma-ray emission from the Crab Nebula (Weekes et al. 1989). Since

Detection of Sub-TeV gamma-rays from the Galactic Center with the CANGAROO-II telescope Ken significant excess at energies greater than 250GeV. This is the first detection of sub-TeV gamma rays from than that predicted previously give IACTs a chance of detecting a gamma-ray #12;signal in the 100 Ge

Mechanically-exfoliated stacks of thin films of Bi2Te3 topological insulators with enhanced; published online 1 October 2010 The authors report on "graphene-like" mechanical exfoliation of single can be used to mechanically exfoliate the ultrathin films of Bi2Te3 with the thickness down

High Efficiency Thin Film CdTe and a-Si Based Solar Cells Final Technical Report for the Period This is the final report covering approximately 42 months of this subcontract for research on high efficiency CdTe-based thin-film solar cells and on high efficiency a-Si-based thin-film solar cells. Phases I and II have

Thin films of Tellurium oxide TeO{sub x} over a wide range of x (2 to 3) were prepared by radio frequency diode sputtering at room temperature on corning glass and quartz substrate. The deposited films are amorphous in nature and IR spectroscopy reveals the formation of Te-O bond. X-ray photoelectron spectroscopy shows the variation in the stoichiometry of TeO{sub x} film from x=2 to 3 with an increase in oxygen percentage (25 to 100%) in processing sputtering gas composition. Raman spectroscopy depicts the formation of TeO{sub 3} trigonal pyramid besides TeO{sub 4} disphenoid in the amorphous TeO{sub x} film with increase in the value of x. The varying stoichiometry of TeO{sub x} thin film (x=2 to 3) was found to influence the optical, electrical, and elastic properties. The optical band gap of film increases from 3.8 to 4.2 eV with increasing x and is attributed to the decrease in density. The elastic constants (C{sub 11} and C{sub 44}) of the deposited films are lower than the corresponding value reported for TeO{sub 2} single crystal.

Spin Hall effect can be induced both by the extrinsic impurity scattering and by the intrinsic spin-orbit coupling in the electronic structure. The HgTe/CdTe quantum well has a quantum phase transition where the electronic structure changes from normal to inverted. We show that the intrinsic spin Hall effect of the conduction band vanishes on the normal side, while it is finite on the inverted side. This difference gives a direct mechanism to experimentally distinguish the intrinsic spin Hall effect from the extrinsic one.

Bulk magnetoresistance quantum oscillations are observed in high quality single crystal samples of BiTeI. This compound shows an extremely large internal spin-orbit coupling, associated with the polarity of the alternating Bi, Te, and I layers perpendicular to the c-axis. The corresponding areas of the inner and outer Fermi surfaces around the A-point show good agreement with theoretical calculations, demonstrating that the intrinsic bulk Rashba-type splitting is nearly 360 meV, comparable to the largest spin-orbit coupling generated in heterostructures and at surfaces.

We are currently developing a handheld radioisotope identifier containing eighteen position-sensitive CdZnTe crystals. In addition to isotope identification, the device performs basic Compton imaging to determine the location of suspected sources. This paper gives an overview of the electronics system we have designed for this instrument. We use specialized application-specific integrated circuits to preprocess the outputs of each CdZnTe crystal. A low-power microprocessor running Windows CE drives the user interface and implements the isotope identification and directionality computations. Finally, we use a field-programmable gate array to perform the computationally intensive imaging tasks in real time.

The switching effect, field and temperature dependences of the permittivity and conductivity of TlGaTe{sub 2} crystals subjected to various {gamma}-irradiation doses are studied. Under rather low electric fields, the phenomenon of threshold switching with an S-shaped current-voltage characteristic containing a portion with negative differential resistance is observed in the crystals. In the region of critical voltages, current and voltage oscillations and imposed modulation are observed. Possible mechanisms of switching, ionic conductivity, disorder, and electrical instability in TlGaTe{sub 2} crystals are discussed.

An efficient ZnTe:O x-ray powder phosphor was prepared by a dry synthesis process using gaseous doping and etching medias. The x-ray luminescent properties were evaluated and compared to standard commercial phosphors exhibited an x-ray luminescent efficiency equivalent to 76% of Gd{sub 2}O{sub 2}S:Tb and an equal resolution of 2.5 lines/mm. In addition, the fast decay time, low afterglow, and superior spectral match to conventional charge-coupled devices-indicate that ZnTe:O is a very promising phosphor candidate for x-ray imaging applications.

Gamma Ray Bursts (GRBs) have been proposed as one {\\it possible} class of sources of the Ultrahigh Energy Cosmic Ray (UHECR) events observed up to energies $\\gsim10^{20}\\ev$. The synchrotron radiation of the highest energy protons accelerated within the GRB source should produce gamma rays up to TeV energies. Here we briefly discuss the implications on the energetics of the GRB from the point of view of the detectability of the prompt TeV gamma rays of proton-synchrotron origin in GRBs in the up-coming ICECUBE muon detector in the south pole.

The superconducting radio frequency photoinjector (SRF gun) is one of the latest applications of superconducting rf technology in the accelerator field. Since superconducting photocathodes with high quantum efficiency are yet unavailable, normal conducting cathode material is the main choice for SRF photoinjectors. However, the compatibility between the photocathode and the cavity is one of the challenges for this concept. Recently, a SRF gun with Cs2Te cathode has been successfully operated in Forschungszentrum Dresden-Rossendorf. In this paper, we will present the physical properties of Cs2Te photocathodes in the SC cavity, such as the quantum efficiency, the lifetime, the rejuvenation, the charge saturation, and the dark current.

The atomic structure and composition of grain boundaries in CdCl2 treated CdTe solar cells have been determined with aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy. A high fraction of Te in the grain boundary regions has been substituted by Cl. Density functional calculations reveal the origin of such segregation levels, and further indicate the GBs are likely inverted to n-type, establishing local P-N junctions, which help to separate electron-hole carriers. The results are in good agreement with electron beam induced current observations of high collection efficiency at grain boundaries.

Topological insulators are new states of quantum matter in which surface states residing in the bulk insulating gap of such systems are protected by time-reversal symmetry. The study of such states was originally inspired by the robustness to scattering of conducting edge states in quantum Hall systems. Recently, such analogies have resulted in the discovery of topologically protected states in two-dimensional and three-dimensional band insulators with large spin-orbit coupling. So far, the only known three-dimensional topological insulator is Bi{sub x}Sb{sub 1-x}, which is an alloy with complex surface states. Here, we present the results of first-principles electronic structure calculations of the layered, stoichiometric crystals Sb{sub 2}Te{sub 3}, Sb{sub 2}Se{sub 3}, Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3}. Our calculations predict that Sb{sub 2}Te{sub 3}, Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} are topological insulators, whereas Sb{sub 2}Se{sub 3} is not. These topological insulators have robust and simple surface states consisting of a single Dirac cone at the point. In addition, we predict that Bi{sub 2}Se{sub 3} has a topologically non-trivial energy gap of 0.3 eV, which is larger than the energy scale of room temperature. We further present a simple and unified continuum model that captures the salient topological features of this class of materials.

to search the entire northern hemisphere for such objects. The search for short bursts of TeV gamma rays hasTeV GAMMA-RAY SURVEY OF THE NORTHERN HEMISPHERE SKY USING THE MILAGRO OBSERVATORY R. Atkins,1,2 W) are presented. The data have been searched for steady point sources of TeV gamma rays between declinations of 1

V energies were observed by the Burst And Transient Satellite Experiment (BATSE) aboard the Compton Gamma-Ray a search for TeV counterparts to -ray bursts. Within the Milagrito #12;eld of view 54 -ray bursts at ke coincident with each of these -ray bursts. For each burst, a circular search region was de#12;ned

efficiency photovoltaic mod- ules. Solar cells with efficiencies of 10 to 16% have been obtained with Cd) is different for different TCOs. This paper describes the effect of CdCl2 treatment on the recrystallization of CdTe, grown on different sub- strates and its influence on the photovoltaic properties of the solar

Flexible glass enables high-temperature, roll-to-roll processing of superstrate devices with higher photocurrents than flexible polymer foils because of its higher optical transmission. Using flexible glass in our high-temperature CdTe process, we achieved a certified record conversion efficiency of 14.05% for a flexible CdTe solar cell. Little has been reported on the flexibility of CdTe devices, so we investigated the effects of three different static bending conditions on device performance. We observed a consistent trend of increased short-circuit current and fill factor, whereas the open-circuit voltage consistently dropped. The quantum efficiency under the same static bend condition showed no change in the response. After storage in a flexed state for 24 h, there was very little change in device efficiency relative to its unflexed state. This indicates that flexible glass is a suitable replacement for rigid glass substrates, and that CdTe solar cells can tolerate bending without a decrease in device performance.

for the solar cell, therefore high specific power (ratio of out- put power to the weight) solar cells]. The high specific power is an important issue for space solar cells: if satellites are lighter1. INTRODUCTION Polycrystalline CdTe thin films solar cells have shown long term stable performance

Neutrino radiation is expected to impose major design and siting constraints on many-TeV muon colliders. Previous predictions for radiation doses at TeV energy scales are briefly reviewed and then modified for extension to the many-TeV energy regime. The energy-cubed dependence of lower energy colliders is found to soften to an increase of slightly less than quadratic when averaged over the plane of the collider ring and slightly less than linear for the radiation hot spots downstream from straight sections in the collider ring. Despite this, the numerical values are judged to be sufficiently high that any many-TeV muon colliders will likely be constructed on large isolated sites specifically chosen to minimize or eliminate human exposure to the neutrino radiation. It is pointed out that such sites would be of an appropriate size scale to also house future proton-proton and electron-positron colliders at the high energy frontier, which naturally leads to conjecture on the possibilities for a new world laboratory for high energy physics. Radiation dose predictions are also presented for the speculative possibility of linear muon colliders. These have greatly reduced radiation constraints relative to circular muon colliders because radiation is only emitted in two pencil beams directed along the axes of the opposing linacs.

From an environmental perspective, lead-free SnTe would be preferable for solid-state waste heat recovery if its thermoelectric figure-of-merit could be brought close to that of the lead-containing chalcogenides. In this ...

Hadronic event shapes have been measured in proton–proton collisions at ?s =7 TeV, with a data sample collected with the CMS detector at the LHC. The sample corresponds to an integrated luminosity of 3.2 pb-1. Event-shape ...

Although the two-loop renormalization group equations for a general gauge field theory have been known for quite some time, deriving them for specific models has often been difficult in practice. This is mainly due to the fact that, albeit straightforward, the involved calculations are quite long, tedious and prone to error. The present work is an attempt to facilitate the practical use of the renormalization group equations in model building. To that end, we have developed two completely independent sets of programs written in Python and Mathematica, respectively. The Mathematica scripts will be part of an upcoming release of SARAH 4. The present article describes the collection of Python routines that we dubbed PyR@TE which is an acronym for "Python Renormalization group equations At Two-loop for Everyone". In PyR@TE, once the user specifies the gauge group and the particle content of the model, the routines automatically generate the full two-loop renormalization group equations for all (dimensionless and dimensionful) parameters. The results can optionally be exported to Latex and Mathematica, or stored in a Python data structure for further processing by other programs. For ease of use, we have implemented an interactive mode for PyR@TE in form of an IPython Notebook. As a first application, we have generated with PyR@TE the renormalization group equations for several non-supersymmetric extensions of the Standard Model and found some discrepancies with the existing literature.

of different materials, including explosives, etc.3Â­6 Development of detectors of la- ser radiation system-indium-doped Pb1-xSnxTe-can be implemented for detection of terahertz radiation yielding extremely- ductivity periodically quenched by short radiofrequency pulses. A remarkable feature is that this material

This Report summarizes the proceedings of the 2013 Les Houches workshop on Physics at TeV Colliders. Session 1 dealt primarily with (1) the techniques for calculating standard model multi-leg NLO and NNLO QCD and NLO EW cross sections and (2) the comparison of those cross sections with LHC data from Run 1, and projections for future measurements in Run 2.

In the past few years, a large body of work has been dedicated to CdTe thin film semiconductors, as the electronic and optical properties of CdTe nanostructures make them desirable for photovoltaic applications. The performance of semiconductor devices is greatly influenced by the deep levels. Knowledge of parameters of deep levels present in as-grown materials and the identification of their origin is the key factor in the development of photovoltaic device performance. Photo Induced Current Transient Spectroscopy technique (PICTS) has proven to be a very powerful method for the study of deep levels enabling us to identify the type of traps, their activation energy and apparent capture cross section. In the present work, we report the effect of growth parameters and LASER irradiation intensity on the photo-electric and transport properties of CdTe thin films prepared by Close-Space Sublimation method using SiC electrical heating element. CdTe thin films were grown at three different source temperatures (630, 650 and 700 °C). The grown films were irradiated with Nd:YAG LASER and characterized by Photo-Induced Current Transient Spectroscopy, Photocurrent measurementand Current Voltage measurements. The defect levels are found to be significantly influenced by the growth temperature.

The Drivetrain of Sustainability Powering innovation in Clean teCh iNSiDe: BUSiNeSS OF HeALTH CARe energy use, generation and storage, as well as other necessities of life, environmentally responsible of Management, I hope to participate in what many expect to be the next big chapter of the California Dream

The primary goal of this study was to ascertain the presence and types of mechanisms affecting CdS/CdTe device stability in the temperature range of 60 to 120 ..deg..C. It should be noted that the results presented were specific to cells made using the specific growth conditions described.

Superconductivity in Topological Insulator Sb2Te3 Induced by Pressure J. Zhu1 *, J. L. Zhang1 *, P superconductivity and topology nature. A s new states of quantum matter, topological insulators are characterized to topological insulators, topological superconductors are expected to have a full pairing gap in the bulk

We have employed the X-Rays Absorption Fine Structure (EXAFS) technique to resolve the local structure of Pb1-xMnxTe (Ga) in order to provide answers on questions concerning the exact positions and charge states of constitutive and impurity atoms, possibilities and features of their ordering and (or) clustering, as well as configurational and thermal disorder in the system.

New Loops! MiTeGen* 50µMicroMountsTM consist of a thin microfabricated polyimide film attached to a solid non-magnetic stainless steel pin. The film is polyimide, which is used in Kapton® tape and is employed for X- ray transparent windows on X-ray beam lines. The film is curved by wrapping polyimide film

A measurement of the ?(0)(b) lifetime using the decay ?(0)(b)?J/?? in protonproton collisions at s?=7 TeV is presented. The data set, corresponding to an integrated luminosity of about 5 fb(?1), was recorded with the CMS ...

A search for three-jet hadronic resonance production in pp collisions at a center-of-mass energy of 7 TeV has been conducted by the CMS Collaboration at the LHC, using a data sample corresponding to an integrated luminosity ...

A search for anomalous production of events with three or more isolated leptons in pp collisions at ?s = 7 TeV is presented. The data, corresponding to an integrated luminosity of 4.98 fb[superscript ?1], were collected ...

The results of the first search for long-lived gluinos produced in 7 TeV pp collisions at the CERN Large Hadron Collider are presented. The search looks for evidence of long-lived particles that stop in the CMS detector ...

The ?(1S), ?(2S), and ?(3S) production cross sections in proton-proton collisions at ?s=7??TeV are measured using a data sample collected with the CMS detector at the LHC, corresponding to an integrated luminosity of ...

detector near Los Alamos, New Mexico, has been operated as a sky monitor at energies of a few TeV between: With the detection of 4 Galactic and 3 extragalatic sources, Very High Energy (VHE) flÂ­ray astronomy, studying the sky at energies above 100 GeV, has become one of the most interesting frontiers in astronomy. Source

Results are reported from a search for the production of three-jet resonances in pp collisions at a center-of-mass energy ?s = 7 TeV. The study uses the data sample collected by the CMS experiment at the LHC in 2011, ...

An inclusive search is presented for new heavy particle pairs produced in ?s=7??TeV proton-proton collisions at the LHC using 4.7±0.1??fb[superscript -1] of integrated luminosity. The selected events are analyzed in the ...

The diffuse gamma radiation arising from the interaction of cosmic ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of the cosmic rays. Milagro is a water Cherenkov detector that continuously views the entire overhead sky. The large field-of-view combined with the long observation time makes Milagro the most sensitive instrument available for the study of large, low surface brightness sources such as the diffuse gamma radiation arising from interactions of cosmic radiation with interstellar matter. In this paper we present spatial and flux measurements of TeV gamma-ray emission from the Cygnus Region. The TeV image shows at least one new source MGRO J2019+37 as well as correlations with the matter density in the region as would be expected from cosmic-ray proton interactions. However, the TeV gamma-ray flux as measured at ~12 TeV from the Cygnus region (after excluding MGRO J2019+37) exceeds that predicted from a conventional model of cosmic ray prod...

The Milagro gamma-ray observatory employs a water Cherenkov detector to observe extensive air showers produced by high-energy particles impacting in the Earth's atmosphere. A 4800 m$^{2}$ pond instrumented with 723 8" PMTs detects Cherenkov light produced by secondary air-shower particles. An array of 175 4000 liter water tanks surrounding the central pond detector was recently added, extending the physical area of the Milagro observatory to 40,000 m$^{2}$ and substantially increasing the sensitivity of the detector. Because of its wide field of view and high duty cycle, Milagro is ideal for monitoring the northern sky almost continuously ($>$90% duty cycle) in the 100 GeV to 100 TeV energy range. Here we discuss the first detection of TeV gamma-rays from the inner Galactic plane region. We also report the detection of an extended TeV source coincident with the EGRET source 3EG J0520+2556, as well as the observation of extended TeV emission from the Cygnus region of the Galactic plane.

We have undertaken a series of single-nucleon and pair transfer reaction measurements to help constrain calculations of the nuclear matrix elements for neutrinoless double beta decay. In this talk, a short overview of measurements relevant to the {sup 130}Te?{sup 130}Xe system is given. Brief mention is made of other recent and forthcoming results.

We have observed exclusive ?? production in proton-antiproton collisions at ?s=1.96??TeV, using data from 1.11±0.07??fb[superscript -1] integrated luminosity taken by the Run II Collider Detector at Fermilab. We selected ...

A measurement of the Z(? ? [superscript +] ? [superscript ?]) + jet production cross-section in pp collisions at a centre-of-mass energy ?s = 7 TeV is presented. The analysis is based on an integrated luminosity of 1.0 ...

Using 1.8??fb[superscript -1] of pp collisions at a center-of-mass energy of 7 TeV recorded by the ATLAS detector at the Large Hadron Collider, we present measurements of the production cross sections of ?(1S,2S,3S) mesons. ...

369 THREE-DIMENSIONAL LUNG DENSITOMETER USING CdTe DETECTORS FOR DIAGNOSIS AND EVALUATION is optimized for lung densitometry, similar configurations can be used for bone densito- metry. - The measurement of absolute lung density by a non-invasive technique is of impor- tance in assessing the status

a red (630 nm) LED with an output equivalent to 1 sun for light data. Red (630 nm) and blue (470 nmCurrent Transients in CdS/CdTe Solar Cells Alan Fahrenbruch Colorado State University Department is completely reversible, with a decay to the DS state. The current/time data were taken using an HP 7090A A

Truman STaTe univerSiTyWELCOME HOME! Air Conditioner Welcome toTruman State University air conditioner requests.If you need air conditioning and are assigned to Centennial,Grim,or Fair conditioning, you will need to bring your own air conditioner unit that is 6000 BTUs or less.A non

Recent observations of the TeV gamma-ray spectra of the two closest active galactic nuclei (AGNs), Markarian 501 (Mrk 501) and Markarian 421 (Mrk 421), by the Whipple and HEGRA collaborations have stimulated efforts to estimate or limit the spectral energy density (SED) of extragalactic background light (EBL) which causes attenuation of TeV photons via pair-production when they travel cosmological distances. In spite of the lack of any distinct cutoff-like feature in the spectra of Mrk 501 and Mrk 421 (in the interval 0.26-10 TeV) which could clearly indicate the presence of such a photon absorption mechanism, we demonstrate that strong EBL attenuation signal (survival probability of 10 TeV photon <10^{-2}) may still be present in the spectra of these AGNs. By estimating the minimal and maximal opacity of the universe to TeV gamma-ray photons, we calculate the visibility range for current and future gamma-ray observatories. Finally, we show that the proposed experiments, VERITAS, HESS, and MAGIC, may even be able to actually measure the EBL SED because their observations extend to the critical 75-150 GeV regime. In this transition region a distinct ``knee-like'' feature should exist in the spectra of blazars, which is invariant with respect to their intrinsic properties. The change of the spectral index and flux amplitude across this knee, if observed for several blazars, will provide missing pieces of information needed to measure EBL in the wavelength range 0.1-30 $\\mu$m.

Lead alloys are extensively used as sheathing material for power and telecommunication cables. Excellent extrusion properties, high ductility, extremely low recrystallization temperature, good fatigue and creep resistance, make these alloys ideal for cable sheathing application. Though the thickness of the lead sheath is only a few hundred {mu}m, it is a critical component of the cable. The lead layer in the cable is often the limiting factor both during the cable production and during its service phase. Up to several hundred miles of long single piece cables may be required for underground and underwater cables. Cracking in the lead sheath during the cable sheathing extrusion limits the production of such long cables while cracking of the lead sheath due to repeated vibration, creep and recrystallization limits the service life of these cables. The purpose of the present research is to increase the duration of cable extrusion time without compromising sheath integrity by minimizing deleterious precipitate formation and growth. Concentrations of Cu and Te in the commercial alloy are too small to contribute to precipitation strengthening. Therefore their positive influence on mechanical strength should mainly result from the influence of Cu and Te in solution on interdiffusivity and grain boundary mobility. The formation of large precipitates observed in Pb-Cu-Te alloys can be minimized and extrusion times increased without negatively affecting mechanical properties if the solute content is reduced to near solid solubility levels. In order to examine the effect of lowering solute content on microstructural stability and mechanical properties, compressive stress-strain behavior of a Pb-50 wt ppm Cu-100 wt ppm Te alloy with solute contents close to the solubility limits and a Pb-400 wt ppm Cu-400 wt ppm Te alloy was examined at room temperature. The grain growth kinetics in these alloys were studied in a temperature range of 100 to 225 C.

GeTe shows promising application as a recording material for phase-change nonvolatile memory due to its fast crystallization speed and extraordinary amorphous stability. To further improve the performance of GeTe, various transition metals, such as copper, have been doped in GeTe in recent works. However, the effect of the doped transition metals on the stability of amorphous GeTe is not known. Here, we shed light on this problem for the system of Cu doped GeTe by means of ab initio molecular dynamics calculations. Our results show that the doped Cu atoms tend to agglomerate in amorphous GeTe. Further, base on analyzing the pair correlation functions, coordination numbers and bond angle distributions, remarkable changes in the local structure of amorphous GeTe induced by Cu are obviously seen. The present work may provide some clues for understanding the effect of early transition metals on the local structure of amorphous phase-change compounds, and hence should be helpful for optimizing the structure and performance of phase-change materials by doping transition metals.

A search for contact interactions has been performed using dimuon events recorded with the ATLAS detector in proton-proton collisions at ?s=7 TeV. The data sample corresponds to an integrated luminosity of 42 pb?¹. No significant deviation from the standard model is observed in the dimuon mass spectrum, allowing the following 95% C.L. limits to be set on the energy scale of contact interactions: ?>4.9 TeV (4.5 TeV) for constructive (destructive) interference in the left-left isoscalar compositeness model. These limits are the most stringent to date for ??qq contact interactions.

. Effective use of criteria such as structural-code cov- erage can help reveal faults. Manually writing test the manual effort, they can employ auto- mated test generation tools that use dynamic symbolic execution (DSE cloud envi- ronment with a fake stub that provides default or user-defined return values to cloud

We have measured the differential cross section for the inclusive production of ?(2S) mesons decaying to ?[superscript +]?[superscript -] that were produced in prompt or B-decay processes from pp? collisions at 1.96 TeV. ...

A search for quark compositeness using dijet angular distributions from pp collisions at sqrt(s) = 7 TeV is presented. The search has been carried out using a data sample corresponding to an integrated luminosity of 2.2 inverse femtobarns, recorded by the CMS experiment at the LHC. Normalized dijet angular distributions have been measured for dijet invariant masses from 0.4 TeV to above 3 TeV and compared with a variety of contact interaction models, including those which take into account the effects of next-to-leading-order QCD corrections. The data are found to be in agreement with the predictions of perturbative QCD, and lower limits are obtained on the contact interaction scale, ranging from 7.5 up to 14.5 TeV at 95% confidence level.

N-type Bi?Te?.?Se?.? bulk thermoelectric materials with peak ZT values up to ?1 were examined by transmission electron microscopy and electron diffraction. Two nanostructural features were found: (i) a structural modulation ...

A measurement of the differential cross section for the inclusive production of isolated prompt photons in proton-proton collisions at a center-of-mass energy of 7 TeV is presented. The data sample corresponds to an ...

We present the first model independent search for three-jet hadronic resonances within multijet events in ?s=1.96??TeV pp? collisions at the Fermilab Tevatron using the CDF II detector. Pair production of supersymmetric ...

Measurements of dijet azimuthal decorrelations in pp collisions at ?s=7??[square root of s=7] TeV using the CMS detector at the CERN LHC are presented. The analysis is based on an inclusive dijet event sample corresponding ...

Results are presented of a search for the production of new particles decaying to pairs of partons (quarks, antiquarks, or gluons), in the dijet mass spectrum in proton-proton collisions at ?s=8??TeV. The data sample ...

339 A SMALL PORTABLE DETECTOR HEAD USING MIS-CONTACTED CdTe FOR X-RAY SPECTROMETRY P. EICHINGER and the implications of this material for the spectroscopy of gamma rays and X-rays. Instead an arrangement

We report on CdS/CdTe photovoltaic devices that contain a thin Ta2O5 film deposited onto the CdS window layer by sputtering. We show that for thicknesses below 5 nm, Ta2O5 films between CdS and CdTe positively affect the solar cell performance, improving JSC, VOC, and the cell power conversion efficiency despite the insulating nature of the interlayer material. Using the Ta2O5 interlayer, a VOC gain of over 100 mV was demonstrated compared to a CdTe/CdS baseline. Application of a 1nm Ta2O5 interlayer enabled the fabrication of CdTe solar cells with extremely thin (less than 30 nm) CdS window layers. The efficiency of these cells exceeded that of a base line cell with 95 nm of CdS.

In this Letter, we present a precise measurement of the total ZZ production cross section in pp? collisions at ?s=1.96??TeV, using data collected with the CDF II detector corresponding to an integrated luminosity of ...

The p-type Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} compounds with Te dopant (4.0 and 6.0 wt%) and without dopant were fabricated by hot extrusion in the temperature range of 300 to 510 C under an extrusion ratio of 20:1. The undoped and Te doped compounds were highly dense and showed high crystalline quality. The grains contained many dislocations and were fine equiaxed ({approximately}1.0 {micro}m) owing to the dynamic recrystallization during the extrusion. The hot extrusion gave rise to the preferred orientation of grains. The bending strength and the figure of merit of the undoped and Te doped compounds were increased with increasing the extrusion temperature. The Te dopant significantly increased the figure of merit. The values of the figure of merit of the undoped and 4.0 wt% Te-doped compounds hot extruded at 440 C were 2.11 x 10{sup {minus}3}/K and 2.94 x 10{sup {minus}3}/K, respectively.

, to a better p-type, to insulating, and then to n-type -- is all due to different levels of Cu involvement treatment temperature. #12;2 I. Introduction CdTe based solar panels have emerged in recent years1 The Roles of Cu Impurity States in CdTe Thin Film Solar Cells Ken K. Chin1 , T.A. Gessert2

In this paper we present the correlation of CdTe solar cell performance with capacitance-voltage hysteresis, defined presently as the difference in capacitance measured at zero-volt bias when collecting such data with different pre-measurement bias conditions. These correlations were obtained on CdTe cells stressed under conditions of 1-sun illumination, open-circuit bias, and an acceleration temperature of approximately 100 degrees C.

The focus of this project is the open-circuit voltage of the CdTe thin-film solar cell. CdTe continues to be one of the leading materials for large-scale cost-effective production of photovoltaics, but the efficiency of the CdTe solar cell has been stagnant for the last few years. At the manufacturing front, the CdTe technology is fast paced and moving forward with U.S.-based First Solar LLC leading the world in CdTe module production. To support the industry efforts and continue the advancement of this technology, it will be necessary to continue improvements in solar cell efficiency. A closer look at the state-of-the-art performance levels puts the three solar cell efficiency parameters of short-circuit current density (JSC), open-circuit voltage (VOC), and fill factor (FF) in the 24-26 mA/cm2, 844?850 mV, and 74%-76% ranges respectively. During the late 1090s, efforts to improve cell efficiency were primarily concerned with increasing JSC, simply by using thinner CdS window layers to enhance the blue response (<510 nm) of the CdTe cell. These efforts led to underscoring the important role 'buffers' (or high-resistivity transparent films) play in CdTe cells. The use of transparent bi-layers (low-p/high-p) as the front contact is becoming a 'standard' feature of the CdTe cell.

Â¯uence on the microstructure of CdTe and photovoltaic properties. Solar cells with efÂ®ciency of 11.2 and 2.5% are obtainedTe/CdS photovoltaic devices have been obtained with different growth methods [1Â±3]. Recrys- tallization treatments. Therefore PVD grown CdS layers are used for better reliability despite of the opti- cal losses due to large

Amorphous nanostructured films of a complex chalcogenide (Ge{sub 2}Sb{sub 2}Te{sub 5}) are produced by laser electrodispersion and their structural and electrical properties are studied. It is found that the characteristic size of Ge{sub 2}Sb{sub 2}Te{sub 5} nanoparticles in the structure of the films is 1.5–5 nm.

We report the results of a search for neutrinoless double-beta decay in a 9.8~kg$\\cdot$yr exposure of $^{130}$Te using a bolometric detector array, CUORE-0. The characteristic detector energy resolution and background level in the region of interest are $5.1\\pm 0.3{\\rm~keV}$ FWHM and $0.058 \\pm 0.004\\,(\\mathrm{stat.})\\pm 0.002\\,(\\mathrm{syst.})$~counts/(keV$\\cdot$kg$\\cdot$yr), respectively. The median 90%~C.L. lower-limit sensitivity of the experiment is $2.9\\times 10^{24}~{\\rm yr}$ and surpasses the sensitivity of previous searches. We find no evidence for neutrinoless double-beta decay of $^{130}$Te and place a Bayesian lower bound on the decay half-life, $T^{0\

Cadmium telluride (CdTe) is a p-type semiconductor used in thin-film solar cells. To achieve high light-to-electricity conversion, annealing in the presence of CdCl{sub 2} is essential, but the underlying mechanism is still under debate. Recent evidence suggests that a reduction in the high density of stacking faults in the CdTe grains is a key process that occurs during the chemical treatment. A range of stacking faults, including intrinsic, extrinsic, and twin boundary, are computationally investigated to identify the extended defects that limit performance. The low-energy faults are found to be electrically benign, while a number of higher energy faults, consistent with atomic-resolution micrographs, are predicted to be hole traps with fluctuations in the local electrostatic potential. It is expected that stacking faults will also be important for other thin-film photovoltaic technologies.